It is narrated from Sayyiduna Sahl bin Sa'd (may Allah be pleased with him); he said: "There was a man among the Companions of the Prophet (peace and blessings be upon him) whose name was Aswad (black), so the Messenger of Allah (peace and blessings be upon him) named him Abyad (white)."
Hadith Referenceالمعجم الكبير للطبراني / باب السين / 5993