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 he emigrated to Madinah, going around to the people at their camps in Mina, and he (peace and blessings be upon him) was saying: "O people, indeed Allah, the Mighty and Majestic, 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. So I asked: Who is this man? The people said: His uncle, Abu Lahab.
Hadith Referenceالمعجم الكبير للطبراني / باب الراء / 4568