It is alleged by critics that when Prophet Muhammad (p) conquered Makkah, he ordered the killing of a slave girl because she was “reciting insulting poems” about Mohammad. He (p) in turn ordered that she be killed.
Scholar, Shaykh Allama Shibli Numani goes into detail on this, showing that the story of Fartana being killed for poetry is not true:
Chroniclers name ten persons, who, notwithstanding the general amnesty granted to the Meccans, were declared to be punishable with death whenever found. Some of them like Abdullah Ibn Khatal and Miqyas Ibn Subaba, stood charged with murder and were executed to pay for the blood they had shed.
But others had only been guilty of torturing and tormenting the Prophet (peace and blessing of Allah be upon him), while at Mecca or composing slanderous verses against him.
One was a woman who had sung satirical songs against the Prophet (p), and was put to death. But this statement when subjected to higher criticism as developed by the traditionists cannot stand scrutiny. Barring a few-not more than half a dozen-which of the Meccans had refrained from active participation in the persecution of the Holy prophet (p). Yet they were all given their freedom.
The victims alleged to have been put to death were answerable for crimes much less serious. Let us remember A’isha (Allah be pleased with her) saying that the Prophet (p) never sought a personal revenge, a report that appears in all Six Books of Authentic Ahadith.
A woman had put poison in his food at Khaibar, but when asked whether she was to be slain, the Prophet’s answer was a clear ‘No’. If a Jewess, guilty of attempting murder by poison could go unharmed, how, on earth could the offenders of Mecca fail to share his mercy, in spite of the fact that they were not charged with anything as black as that.
But let alone this logical criticism, we shall have to admit that the story even if judged on the basis of reports, is unacceptable. Sahih al-Bukhari mentions the execution of Ibn Khatal alone, and this is admitted on all hands that he was executed for a murder.
The execution of Miqyas too was a retaliatory sentence. All such reports, as ascribe the execution of others merely to their having harassed the Prophet (p) in the past, have Ibn Ishaq as the last narrator at the top; and in the terminology of the traditionists such reports are called Mursal and are not to be relied on.
The most reliable report that can be referred to in this connection is the one mentioned in Abu Dawud, which says that on the day when Mecca fell, the Prophet (p) declared that four persons could not be promised immunity. But Abu Dawud adds that for this report he could not find authoritative sources of desired merit.
Then he quotes the report about Ibn Khatal. The report quoted earlier has Ahmad Ibn Mufaddal as one of the narrators, whom Azdi calls a narrator of Munkar traditions. Another link in the series has Isbat Ibn Nadr whom Nasa’I does not believe to be quite weighty.
Certainly flaws are not enough to make up a good case for rejecting a narration. Yet in view of the importance of the issue in hand even this much of deficiency is enough to create doubts.
It is certain that some of the Meccan notables who formed the vanguard of the opposition did flee away from Mecca when the approach of the Prophet (p) came to be known. That they left because of death sentence is a mere product of Ibn Ishaq’s imagination.
Ibn Ishaq names Ikrimah, the son of Abu Jahl, as well as one of the proclaimed culprits. In Muwatta by Imam Malik, which in accuracy and reliability has, according to Imam Shafi’I, no equal under the sun except the Qur’an, this incident has been narrated as below: ‘Umm Hakim, daughter of Harith Ibn Hisham, was the wife of Ikrima, son of Abu Jahl.
She embraced Islam on the day Mecca fell. But her husband Ikrima Ibn Abu Jahl fled to Yemen, to keep away from Islam. He believed and came to Mecca.
As the Prophet (p) saw him, he rose to his feet in joy and walked up to him in a hurry, even without the upper garment (s sheet of cloth) on his body. The Prophet (p) then initiated him into Islam. It must also be noted that those who were granted protection were not forced to embrace Islam.
Historians and biographers have all stated that the Muslim force at the battle of Hunain, which took place a little after the Fall of Mecca, had in its ranks a good number of non-believers from Mecca who still stuck to their old beliefs. And it was their presence that brought on defeat, for they could not stand the first assault, and this disorder forced the Muslims to follow suit. 
Allama Shibli provides more evidence in his footnotes. He writes:
Footnotes for page 199 to 203
2. Hafiz Mughlata’I, enumerates fifteen names from various sources, and these in themselves are not very reliable in the opinion of the traditionists. Other writers in general have given ten names. Ibn Ishaq has given eight and Abu Dawud and Dar Qutni only six. Bukhari has described the execution of Ibn Khatal alone. This shows that the number fell with every advance in research and enquiry.
The generally current report has it that the ten persons condemned to death were criminals of the blackest water. Seven of them embraced Islam and they were forgiven. Only three were executed- two men and one woman, namely Abdullah Ibn Khatal, Miqyas Ibn Subaba [Page 200] and Quraiba, the slave girl of Ibn Khatal. Ibn Khatal first a convert to Islam, had killed a slave of his and then turned an apostate.
As to Miqyas Ibn Subaba a brother of his had been killed by an Ansari, but the Holy Prophet (p) had paid his blood-money. Later on Miqyas affected a false conversion and then found some pretext to kill the Ansari; Huwairith had created trouble for the two daughters of the Prophet (p) while they were leaving Mecca for good.
He had tried to push them down from the camel’s back. He was killed by Ali. Quraiba, the slave girl of Ibn Khatal, was a Meccan songstress, who sang slanderous and defamatory verses against the Prophet (p). See Zurqani and Ibn Hisham, chapter Conquest of Mecca.
2. In the chapter on the ‘Execution of the Captives’ Abu Dawud records three reports bearing on this topic. The first one recorded has been referred to by the author last of all. This one comes down through Ahmad Ibn al-Mufaddal, Isbat Ibn Nadr, Suddi Kabir, Musa Ibn Sa’d and Sa’d Ibn Abi Waqqas.
It states four men and two women having been sentenced to death of whom one is Ibn Abi Sarh who was produced before the Prophet without his consent by Uthman. Uthman hesitated for a time and then promised protection to him and he then turned a Muslim.
In connection with this report the integrity of three narrators, Isbat Ibn Nadr, Ahmad Ibn Mufaddal and Suddi Kabir has been questioned by the traditionists, the more particularly that of Isbat Ibn Nadr. Nasa’I in the chapter on the ‘Execution of Apostates’ and Hakim in Mustadrak in the Book on Maghazi record this report with the same chain of narrators.
All the three narrators named above in this series are Shi’ah as pointed out by Hakim in his Mustadrak. The second report in Abu Dawud comes through Umar Ibn Uthman Ibn Abd al-Rahman Ibn Sa’id Makhzumi. Umar having received it from his father.
The report says that the Prophet refused protection to four men and two women who were both songstresses, one got converted and the other was put to death. Of this report Abu Dawud says that he could not completely [Page 202] grasp the sources of this report even with the help of his teacher Abu al-Ala. Again, this report with the same chain appears in Dar Qutni towards the end of the chapter on Pilgrimage. The chain ends with the words ‘Umar had it from his father.’
It is evident that Abu Dawud looks upon this portion of the chain as doubtful. The third report in Abu Dawud speaks of a single execution, namely that of Ibn Khatal, which is corroborated by Bukhari. Baihaqi records a report coming down from Hakim Ibn Abd al-Malik, Qatada and Anas Ibn Malik, which states three men and one woman as having been executed.
The three men are Ibn Khatal, Miqyas Ibn Subaba and Abdullah Ibn Sa’d Ibn Abi Sarh, the woman was one Umm Sarh by name. An Ansari had promised to kill Abdullah Ibn Sa’d, but he was spared through the intercession of Uthman, and Umm Sarh is no other than the woman who carried the secret letter telling the Muslim advance towards Mecca.
In this report Hakim Ibn Abd al-Malik is unanimously believed to be unreliable and Aqili writes that none of his associates corroborates this report. For details see Tahdhib of Ibn Hajar. 
 Sirat -un- Nabi By Shaykh Allama Shibli Numani – Volume 2, page 199 – 203
 Sirat -un- Nabi By Shaykh Allama Shibli Numani – Volume 2, page 199 – 203