Sahih Muslim
The Book of Faith (Kitab Al-Iman)
Book Number: 001 / Hadith Number: 38
It is narrated on the authority of Abu Huraira that the Messenger of Allah said to his uncle (at the time of his death): Make a profession of it that there is no god but Allah and I will bear testimony (of your being a Muslim) on the Day of judgment. He (Abu Talib) said: Were it not the fear of the Quraysh blaming me (and) saying that it was the fear of (approaching death) that induced me to do so, I would have certainly delighted your eyes. It was then that Allah revealed:
" Verily thou canst not guide to the right path whom thou lovest. And it is Allah Who guideth whom He will and He knoweth best who are the guided" (xxviii-56).