Is this a contradiction Between:
“THE GUIDING OF THEM IS NOT THY DUTY (O Muhammad), but Allah guideth whom He will. And whatsoever good thing ye spend, it is for yourselves, when ye spend not save in search of Allah’s Countenance; and whatsoever good thing ye spend, it will be repaid to you in full, and ye will not be wronged.”
But “And those who disbelieve say: Why has not a sign been sent down upon him from his Lord? YOU ARE ONLY A WARNER AND A GUIDE FOR EVERY PEOPLE.” (Quran 13:7)
In the name of Allah exalted He the beneficent and the most Merciful.
There are in these two beautiful verses two types Of Guidance:
1) Guidance of the heart and blessing from Allah exalted He on a non-Muslim to open his heart and make him/her accept Islam
2) Second type of Guidance is the Guidance to the Straight path of Islam which is Prophet Muhammed peace be upon him Job and all Muslim Preachers Job is to guide people to the Straight Path of Islam and WARN them about the dangers of not accepting Islam
Prophet Muhammed and all Muslim preachers do not own the first type of Guidance which is Guidance of the heart and blessing from Allah exalted He on a non-Muslim to open his heart and make him/her accept Islam.
This type of guidance is a blessing from Allah exalted he bestowed on anyone who is a genuine truth seeker and ready to open his/her heart, mind and soul for the absolute truth and beauty of the oneness and monotheism in Islam and worship the true Lord of all worlds Allah exalted He.
Hope this answer explains any false perceived superficial misunderstanding about those holy beautiful verses
Allah Knows Best.