Jubayr bin Nufayr narrates: Abu Dharr (may Allah be pleased with him) used to say: "I saw myself as the fourth in Islam; no one had accepted Islam before me except the Prophet (peace and blessings be upon him), Abu Bakr and Bilal (may Allah be pleased with them both)."
Hadith Referenceالمعجم الكبير للطبراني / باب الجيم / 1605