Sayyiduna Abdullah bin al-Zubayr (may Allah be pleased with them both) said: "The name of Abu Bakr (may Allah be pleased with him) was Abdullah bin Uthman, and the Messenger of Allah (peace and blessings be upon him) gave him the title 'Atiq' (the one freed from the Fire)."
Hadith Referenceالمعجم الكبير للطبراني / باب العين / 13833