Muhammad bin Aqil narrates: Sayyiduna Ali bin Abi Talib (may Allah be pleased with him) addressed us in a sermon and said: "O people, tell me, who is the bravest of people?" The narrator says: or perhaps these were the words: We said: "You, O Commander of the Faithful!" Sayyiduna Ali (may Allah be pleased with him) said: "As for me, whoever I challenged to single combat, I got the better of him. But tell me who the bravest of people is." The people said: "We do not know who it is." Sayyiduna Ali (may Allah be pleased with him) said: "Abu Bakr. On the day of the Battle of Badr we prepared a shelter for the Prophet (peace and blessings be upon him), and we wondered who would stay with the Prophet (peace and blessings be upon him) so that none of the polytheists could get at him. By Allah, no one came close to the Prophet (peace and blessings be upon him) except Sayyiduna Abu Bakr (may Allah be pleased with him). He stood with his sword drawn at the head of the Prophet (peace and blessings be upon him); whoever tried to reach the Prophet (peace and blessings be upon him), Sayyiduna Abu Bakr (may Allah be pleased with him) would go for him. So he was the bravest man." Sayyiduna Ali (may Allah be pleased with him) said: "I remember about the Prophet (peace and blessings be upon him) that the Quraysh seized him; one was pushing him and another was pulling him, and they were saying: 'Are you the one who says that there is only one god?'" Sayyiduna Ali (may Allah be pleased with him) said: "By Allah, at that time none of us came near him; only Sayyiduna Abu Bakr (may Allah be pleased with him) came forward, striking one, pushing another away and pulling another, while saying: 'Woe to you! Do you want to kill a man because he says: My Lord is Allah?'" Then Sayyiduna Ali (may Allah be pleased with him) lifted the cloak he was wearing and wept until his beard became wet. Then Sayyiduna Ali (may Allah be pleased with him) said: "I ask you by Allah, is the believer from the people of Pharaoh better, or is Sayyiduna Abu Bakr (may Allah be pleased with him) better?" The people remained silent, so Sayyiduna Ali (may Allah be pleased with him) said: "Why do you not answer me? By Allah, a single hour of Sayyiduna Abu Bakr (may Allah be pleased with him) is better than the like of the believer from the people of Pharaoh, for that man concealed his faith, while this man proclaimed his faith."
Bazzar recorded it. Its chain contains a narrator whom I do not know.
Hadith Referenceمجمع الزوائد ومنبع الفوائد / كتاب المناقب / 14333