Narrated A man from the Ansar:
that Zaid bin Al-Arqam said: "The first to accept Islam was 'Ali."'Amr bin Murrah said: "So I mentioned that to Ibrahim An-Nakha'i, so he rejected that and said: 'The first to accept Islam was Abu Bakr As-Siddiq.'" (RU)
English reference (RU): Vol. 1, Book 46, Hadith 3735 (RU)
Arabic reference (RU): Book 49, Hadith 4100 (RU)