It is narrated from Sayyiduna Abu Hurairah (may Allah be pleased with him) that the Messenger of Allah (peace and blessings be upon him) said to his uncle (Abu Talib): “Acknowledge «لا الهٰ الا الله» so that I may testify in your favor on the Day of Resurrection.” He replied: If it were not that the Quraysh would reproach me, I would acknowledge it before you. Then Allah the Exalted revealed this verse: «إِنَّكَلَاتَهْدِيمَنْأَحْبَبْتَوَلَـكِنَّاللَّـهَيَهْدِيمَنيَشَاءُوَهُوَأَعْلَمُبِالْمُهْتَدِينَ»[28-القصص:56] “You cannot guide whom you love, but Allah guides whom He wills, and He knows best those who are guided.”
Hadith Referenceمسند اسحاق بن راهويه / كتاب الايمان / 37
Hadith Takhrij«مسلم ، كتاب الايمان ، باب الدليل على صحة الاسلام الخ ، رقم : 25 . سنن ترمذي ، رقم : 3188 . سنن نسائي ، رقم : 2035»