Sayyiduna Rabi'ah bin Ibad (may Allah be pleased with him) said: I saw the Messenger of Allah (peace and blessings be upon him) before the emigration in the market of Dhul-Majaz, going around among the people and saying: "O people, indeed Allah commands you to worship Him and not to associate anything with Him." Behind him (peace and blessings be upon him) was a man saying: O people, this man is ordering you to abandon the religion of your forefathers. I asked: Who is this? The people said: His uncle, Abu Lahab.
Hadith Referenceالمعجم الكبير للطبراني / باب الراء / 4572