Some men from the clans of Adal and Qarah came to Prophet Muhammed (p) in Madinah, requesting the Prophet (p) to send some of his men to their tribes, to learn more about Islam. When the Muslims were on their way, near a place called al-Raji they got betrayed and got ambushed by Banu Lihyan tribe. All the Muslims were killed.
Kitab Al-Tabaqat Al-Kabir – Ibn Sa’d:
“SARRIYAH OF MARTHAD IBN ABI MARTHAD
Then (occurred) the sariyyah of Marthad Ibn Abi Marthad al-Ghanawi towards al-Raji in Safar after the commencement of the thirty-sixth month from the hijrah of the Apostle of Allah.
A group of the Adal and al-Qarah, who were connected with al-Hun Ibn Khuzaymah, came to the Apostle of Allah, and said: O Apostle of Allah! There is Islam in us (i.e. has been introduced among us) so send some of your Companions to teach us al-Qur’an and make us understand it and instruct us in the laws of Islam. The Apostle of Allah, sent a party of ten persons
(1) Asim Ibn Thabit Ibn al-Aqlah,
(2) Marthad Ibn Abi Marthad,
(3) Abd Allah Ibn Tariq, (4) Khubayb Ibn Ai,
(5) Zayd Ibn al-Dathinah, (6) Khalid Ibn Abi al-Bukayr,
(7) Mu’attib Ibn Ibayd, uterine brother of Abd Allah Ibn Tariq, both (the brothers) belonged to Balli tribe and were allies of Banu Zafar. He (Prophet) appointed Asim Ibn Thabit as their leaer, and another narrator said: (He appointed) Marthad Ibn Abi Marthad.
They set out and reached al-Raji which is a spring of Hudhayl on the way to al-Hadah. Al-Hadah is seven miles from it (al-Raji) and seven miles from Usfan. They (Adal and al-Qarah) behaved treacherously to them and sought the help of Hudhayl against them (Muslims). Banu Lihyan marched against them…” 
“THE DAY OF AL-RAJI, A.H. 3
… They said that some of them had already accepted Islam and they asked him to send some of his companions to instruct them in religion and teach them to read the Quran and to teach them the laws of Islam. The Apostle sent the following six of his companions Marthad b. Abu Marthad al-Ghanawi, an ally of Hamza; Lhalid b. al-Bukayr al-Laythi, an
ally of b. Adiy b. Ka’b; Asim b. Thabit b. Abu’-Aqlah, brother of b. Amr b. Auf b. Malik b. al-Aus; Khubayb b. Adiy, brother of b. Jahjaba b. Kulfa b. Amr b. Zurayq b. Abdu Haritha b. Malik b. Ghadb b. Jusham b. al-Kazraj; Abdullah b. Tariq, ally of b. Zafar b. al-Khazraj b. Amr b. Malik b. al-Aus.
The Apostle put Marthad in comman of them and the band got as far as al-Raji, a watering-place of Hudhayl in a district of the Hijaz at the upper part of al-Had’a. There they betrayed them and summoned Hudhayl against them.
While they were off their guard sitting with their baggage suddenly they were set upon by men with swords in their hands, so they took their swords to fight them; but the men said that it was not their intention to kill them; they wanted to get something for them from the people of Mecca. They swore by God that they would not kill them.” 
“For the story of how a group of men from the clans of Adal and al-Qarah came to Muhammed in Medina in A. H. 4 and asked for me to instruct them in Islam and how, after Muhammed had sent six men back with them (including Khubayb b. Adi), they betrayed the six to the pro-Meccan Lihyan sub-tribe of Hudhayl (which had a vendetta against the Muslims) at the watering place of al-Raji…” 
Shaykh Allamah Shibli Nomani:
At about the same time some men belonging to the tribe of Adul and the Qara approached the Prophet (p) with a request to send men to instruct their tribesmen in the Islamic ways as they had come under Islam. The Prophet (p) sent out ten persons whose leader was Asim Ibn Thabit.
When they reached Raji, place midway between Usfan and Mecca, these treacherous fellows betrayed the Muslims and prompted the Banu Lahyan to kill them all. The Banu Lahyan pursued them with two hundred tribesmen, half of whom were bowmen. The foe had nearly overtaken the Muslims, when they tried to escape by ascending on to a mound.
The bowmen asked them to come down and promised protection. ‘I do not want to protection of an infidel’, replied Asim. Then addressing God he prayed to Him to let His Prophet know of all that. In short Asim, with seven others, put up a good fight till all of them were killed.
(The Quraish sent a party of men to fetch them a piece of flesh from Asim’s body so that he might be identified. But God would not allow such a disgraceful desecration of a Muslim martyr.
Bees swarmed over the dead body, and the men sent by the Quraish had to return unsuccessful. Three of the Muslims, two of whom were Khubaib and Zaid, did not distrust the words of the infidels, and came down from the mound. The infidels played false and had them bound. They were later on sold as slaves in Mecca. In the battle of Uhud, Khubaib had killed Harith
Ibn Amir; so the sons of Harith purchased him with a view to killing him in revenge. For a few days he stayed at their house. One day he happened to be playing with the granddaughter of Harith, while he had a knife in his hand.2 Accidently the mother of the child came up.
The sight of a naked knife in the hand of Khubaib sent through her body a shudder of fear. ‘Did you think’, said Khubaib, ‘I would slaughter your child with this knife. No that is not our way.’
The members of Harith’s family took him outside the precincts of Harm and wanted to slay him.3
He asked for permission to offer rak’at of prayer. The murderers allowed him this much respite. He offered two rak’at and then said, ‘I had a mind to continue my prayers much longer, but you might perhaps think I was afraid of death.’
Then he recited the following couplet:
‘When I am to be slain for embracing Islam, I care not in what manner I shall be slain. All this is for the sake of God and if He wills He will shower His blessings on the severed pieces of my body.’
(It has since then been customary that whosoever is condemned to death is allowed to offer two rak’at of prayer before being executed;1 and it is considered commendable).2
The second man was Zaid, whom Safwan Ibn Mu’awiya had purchased with the intention of killing him. All the dignitaries of the Quraish assembled to witness his slaughter; and Abu Sufyan was one of them. When the executioner eased his sword, Abu Sufyan said,
‘Tell us the truth, if Muhammad were slain in your place, would you not think it lucky for yourself.’ ‘By God’, retorted Zaid, ‘I would sooner give up this life than see a single thorn prick the foot of the Messenger of Allah.’
This said, Nistas, the slave of Safwan struck his head off.” 
Hajjah Amina Adil:
“THE DAY OF RAJI
The same year some men from the lesser tribes of Adal and al-Qara came to the Holy Prophet saying, We have accepted Islam and are therefore in need of some instruction. Please send us some people who can teach us what we need to know of Islam.’ The Holy Prophet sent Asim bin Thabit of Aws back with them, together with fourteen companions.
When they had reached a watering-place called Raji between Asfan and Mecca, the hypocrites of the tribe of Hudhail made plain the treacherous villainy within their hearts, and betrayed them by summoning the other branches of Hudhail for support against them. When the Bani Lihyana of Hudhail received this call, they sent one-hundred archers and two-hundred warriors to lie in wait for the Muslims.
The Muslims realized the situation and immediately sought refuge behind a mountain. The unbelievers surrounded the mountain and called out,
‘If you give yourselves up, you may get away with your lives, otherwise we shall kill you.’ The Muslims answered,
‘We are Muslims and we are disciples of Muhammad, the Prophet. We will never accept quarter from an unbeliever.’
Asim raised his hands and prayed to the Lord, his heart burning within him, ‘Oh Allah, I have only one request, and that is that You should make known to Your Beloved Muhammad the plight of this handful of believers, that is all I would pray for at this moment.’ For these great Sahaba (companions) it was of the utmost importance that the Beloved of Allah, the Holy Prophet be satisfied and pleased with them, more so even than attaining the everlasting peace and bliss of Paradise.
The station of these Sahaba (companions)was that of soldiers of Love, and Love means giving pleasure to the beloved; the Lover desiring the pleasure of his Beloved strives neither glory nor for abasement. Therefore, Asim prayed to the Lord to make known to the Holy Prophet that they went gladly to receive martyrdom for the cause of Islam.
‘Through the means of Your Power make it known to him,’ he prayed, and his prayer was accepted. As he was dying a martyr, Allah showed to His Holy Prophet through spiritual communication that he had gone to the Presence of the Lord along with his Companions. Also, he learned that two of the Muslims had been captured, Khubayb of Aws and Zayd of Khazraj. The Prophet informed his Companions of this without having left Madinah.
The unbelievers sent out some men to bring a part of Asim’s dead body, (his skull, as at Uhud he had killed two of the standard-bearers of Quraysh whereupon their mother had sworn she would drink wine from his skull), but as he was dying, Asim had made yet another supplication to his Lord:
‘Of Lord, do not let the enemy touch my dead body.’ The word of this great Lover of the Divine caused a great swarm of bees to appear on the material plane and set about his body so that the men sent by the idolaters could not approach from the density of that insect and had to turn back.
As for the two captives, they were bound and brought back to Mecca and sold there. Khubayb was bought by the sons of Harith bin Amr whom he had killed in the Battle of Uhud, who sought to avenge their father’s death. At one point during his imprisonment Khubayb called for a razor with which to clean himself before he was to die. The wife of Harith bin Amr saw him.
Then she noticed that the three-year old grandson of Harith bin Amir was playing close by. The woman began to scream with fright, saying, ‘Now he will kill that child, he knows you intend to kill him, he will avenge himself on that child.’
But Khubayb answered her, ‘Don’t worry, have no fear, for we are of those who have sat with Muhammad and taken our lessons from the Holy Qur’an. We are believers of him who is a mercy for the worlds. Feelings of revenge, have no place with us, nor are we of those who act on the impulse of their egotistic drives, we will raise the word against a man only in the name of Allah.’” 
Bashīr Aḥmad M.A.:
“Treachery of the Disbelievers and the Incident of Rajī‘ – Ṣafar 4 A.H.
These were days of grave danger for the Muslims and the Holy Prophet was receiving horrific news from all four ends. However, the greatest danger posed to the Holy Prophet was from the Quraish of Makkah, who had grown very bold and daring due to the battle of Uḥud.
Perceiving this threat, in the month of Ṣafar 4 A.H., the Holy Prophet assembled a party of ten Companions, appointed ‘Aṣim bin Thabitra as their Amir and ordered them to secretly go towards Makkah and obtain intelligence with regards to the Quraish, and then inform him about their plans and motives.1
However, this party had not yet departed, when a few people from the tribes of ‘Aḍal and Qārah presented themselves before the Holy Prophet, and said that many people from among their tribes were inclined towards Islam and that the Holy Prophet should send a few men with them, who could convert them to Islam and educate them.
The Holy Prophet was happy to hear their request and the same party which had been assembled for the reconnaissance mission was sent off with them instead.
However, in actuality, as was later discovered, these people were liars and had come to Madinah upon the incitement of the Bana Laḥyan, who sought revenge for the execution of their chief, Sufyan bin Khalid, and had thus contrived the plan that when the Muslims come out of Madinah on this pretense, they would attack them. In lieu of this service, the Banū Laḥyān promised the people of ‘Aḍal and Qarah a hefty reward of many camels.
When the treacherous people of ‘Adal and Qarah reached between ‘Asfan and Makkah, they secretly sent word to the Banu Laḥyan that the Muslims were accompanying them and that they should come as well. Upon this, 200 young men from the Banu Laḥyan, 100 of whom were archers, set forth in pursuit of the Muslims, and subdued them at a place known as Raji‘.
But how could 10 men compete against 200 warriors? The Muslims, however, had not been taught to throw in their arms.
The Companions immediately ascended to a nearby hillock and prepared for battle. The disbelievers, who did not consider deception as being reprehensible, called out to them and said, “Come down from the mountain, we give you a firm promise that we shall not kill you.” ‘
Aṣim responded, “We have no confidence whatsoever in your treaties and agreements. We cannot descend on your guarantee.” Then, he raised his head towards the heaven and said, “O God! You are witnessing our state. Do convey knowledge of our condition to Your Messenger.”
Hence, ‘Aṣim and his Companions stood and fought and were finally martyred in battle. When seven Companions had been put to death, and only Khubaib bin ‘Adiyyra, Zaid bin Dathinah, and one other Companion were left, the disbelievers whose actual desire was to capture these people alive, called out again and said, “There is still time. Come down and we promise not to cause you any harm.” This time, these innocent Muslims fell into their trap and descended.
However, as soon as they stepped down, the disbelievers tied them with the strings of their arrow bows. Upon this, the Companion of Khubaib and Zaid, whose name has been recorded in history as being ‘Abdullah bin Ṭariq, could not restrain himself and called out, “This is your first breach of agreement and who knows what you shall do hereafter,” and ‘Abdullah refused to continue along with them.
For some distance, the disbelievers dragged ‘Abdullah along, beating and assaulting him, and then killed him and left him for dead. Moreover, now that there revenge had been sought, in order to please the Quraish, and also in the greed of money, they took Khubaib and Zaid and made way to Makkah; upon reaching there, they sold both of them to the Quraish.
As such, Khubaib was purchased by the sons of Ḥarith bin ‘Amir bin Naufal, because Khubaib had slain Ḥarith in the battle of Badr and Zaid was purchased by Ṣafwan bin Umayyah.
These two Companions were still in a state of captivity when one day Khubaib asked the daughter of Ḥarith if he could be given a razor for his own personal use, and she gave him one. When Khubaib was holding this razor, a small child of the daughter of Ḥarith happened to come over to Khubaib playing here and there; and he placed him on his thigh.
When the mother saw that Khubaib was holding a razor in his hand and her child was sitting on his thigh, she began to tremble and her face turned pale in fear. When Khubaib saw her, he understood that she was fearful and said, “Do you think that I will kill this child?
Do not think this. God-Willing, I shall never commit such an act.” Upon hearing these words, the faded countenance of the mother lit up. This lady was so deeply influenced by the high moral character of Khubaib that afterwards, she would always say, “I have never seen a prisoner as good as Khubaib.”
She would also say, “On one occasion, I saw a bunch of grapes in the hand of Khubaib and he was picking grapes one by one and eating them, although there was no sign of grapes in Makkah during those days and Khubaib was shackled in strong iron chains.” She says,
“I believe that these were heavenly provisions which would come to Khubaib.”
However, before the heartfelt enmity of the Quraish, emotions of mercy and justice were out of the question. As such, it had not been many days when the people of the Banū Al-Ḥārith and other chieftains of the Quraish took Khubaib to an open field in order to execute him and celebrate his death.
When Khubaib perceived the fragrance of martyrdom, he implored the Quraish to allow him an opportunity to offer two Rak‘at of Ṣalat before his death. The Quraish, who perhaps desired to make the Islamic worship a part of this spectacle, granted him permission.
Khubaib offered two Rakat of Ṣalat with great attention and concentration. After completing his ṢalAt, he said to the Quraish, “I desired to prolong my Ṣalat even more, but then I thought that you may assume that I am prolonging my Ṣalat with the intention of deferring death.”
Then, reciting the following couplets, Khubaib leaned forward: “When I am being martyred in the cause of Islam as a Muslim, I care not as to which flank I fall upon after being martyred, all of this is for the sake of God;And if my God so wills, He shall bless my every severed limb.”
The last words of these couplets were perhaps still echoing from the tongue of Khubaib when ‘Uqbah bin Ḥarith stepped forward and this lover of the Holy Prophet was mixed to dust.
In another narration it is related that the Quraish hung Khubaib to the branch of a tree and then murdered him by repeatedly piercing him with lances. An individual by the name of Sa‘id bin ‘Amir was also among the crowd.
Afterwards, he become Muslim and even until the reign of the Khilafat of Ḥaḍrat ‘Umar, whenever he would remember the incident of Khubaib, he would be overtaken by a state of swoon. To the other side, Ṣafwan bin Umayyah took his prisoner Zaid bin
Dathinah outside the Ḥaram. A crowd consisting of the chieftains of Makkah accompanied him. Upon reaching outside the Ḥaram, Ṣafwan ordered his slave Nasṭas to execute Zaid. Nasṭas stepped forward and raised his sword. At this instance, Abu Sufyān bin Ḥarb, the chieftain of Makkah who was also among the spectators stepped forward.
And addressed Zaid saying, “Tell the truth, does your heart not desire that on this instance, in your stead Muḥammad was in our hands, and we would execute him while you would be spared to spend days of joy with your family?”
The eyes of Zaid began to gorge with blood in rage and he furiously retorted, “Abu Sufyan! What nonsense do you utter? By God! I would not even prefer that in lieu of me being spared a thorn were to prick the foot of the Messenger of Allah!” Abu Sufyan uncontrollably proclaimed,
“By God, I have never seen any individual love another person as much as the Companions of Muḥammad love Muḥammad .” After this, Nasṭas martyred Zaid.
In the context of this very incident of Raji‘, a narration has been related that when the Quraish received news that ‘Aṣim bin Thabit was also among those who had been martyred at Raji‘ at the hands of the Banu Laḥyan, since ‘Aṣim had slain a principal chieftain of the Quraish, they especially sent some men towards Raji‘, and emphatically instructed them to return with the head of ‘Aṣim or another part of his body.
so that they could be put to rest and their thirst for revenge could be quenched. It is related in another narration that the mother of the person whom ‘Aṣim had slain had vowed that she would drink alcohol in the skull of her son’s killer.
However, the power of God was such that when these people arrived there, lo and behold, they found swarms of hornets and male honey bees resting upon the body of ‘Aṣim and they just would not budge. These people tried their level best to send off these hornets and bees, but no attempt proved successful. Finally, with no other choice, they returned frustrated and unsuccessful.
Soon after, a storm of rain came and took the body of ‘Aṣim elsewhere. It is written that upon accepting Islam, ‘Āṣim vowed that he would completely abstain from anything that was polytheistic, to the extent that he would not even touch an idolator.
When Ḥaḍrat ‘Umar was informed of his martyrdom and of this occurrence in particular, he said, “Look how beautifully Allah guards the emotions of his beloved servants. He fulfilled the vowed of ‘Aṣim even after his demise and safeguarded him from the touch of idolators.”
The grief which the Holy Prophet and his Companions would have felt as a result of the incident of Raji‘ is obvious. However, before this tragic news could reach Madinah, another incident took place. Hence, before we comment on the incident of Raji‘, it is necessary to mention this incident, because both these occurrences were similar in nature, and the Holy Prophet received news of them at the same time as well.” 
 Kitab Al-Tabaqat Al-Kabir by Ibn Sa’d, page 66 – 68
 Ibn Ishaq’s Sirat Rasul Allah – The Life of Muhammad Translated by A. Guillaume, page 426
 The History of al-Tabari – The Victory of Islam: Muhammad at Medina [Michael Fishbein – Translator], volume 8, page 16, footnote 84
 Sirat -un- Nabi [Sallallahu Alaihi Wasallam] By Shaykh Allamah Shibli Nomani (r.a) – Volume 2, page 79 – 81
 Muhammad, the Messenger of Islam: His Life & Prophecy By Hajjah Amina Adil, page 358 – 359
 The Life & Character of the Seal of Prophets (Sirat Khatamun-Nabiyyiin) By Mirza Bashir Aḥmad M.A.,volume 2, page 362 – 365