Mustadrak al-Hakim — Hadith 4471

Sayyiduna Ibrahim bin Abd al-Rahman bin Awf narrates from his father that Sayyiduna Abd al-Rahman bin Awf was with Umar bin al-Khattab, and that Muhammad bin Maslamah had broken the sword of al-Zubayr. Then Abu Bakr stood up, addressed the people and, offering them his excuse, said: "By Allah, I was never eager for leadership, neither by day nor by night, nor did I desire it, nor did I ever ask Allah, the Mighty and Majestic, for it, secretly or openly. But I feared discord (fitnah). There is no comfort for me in leadership; rather, a great responsibility has been placed upon me for which I have neither the capacity nor the strength, except that Allah, the Mighty and Majestic, grants strength. I wished that the one most capable of bearing it were in my place today." So the Muhajirun accepted what he said and his excuse, and Ali and al-Zubayr (may Allah be pleased with them both) said: "We were only upset because we were kept back from the consultation. We regard Abu Bakr (may Allah be pleased with him) as the most deserving of people for this leadership after the Messenger of Allah (peace and blessings be upon him). Indeed, he is the companion of the cave and 'the second of the two' [Surah al-Tawbah: 40]. We know his honour and his seniority, and the Messenger of Allah (peace and blessings be upon him) ordered him to lead the people in prayer during his lifetime."
This hadith is sahih (authentic) on the condition of the two Shaykhs, but they did not record it.