Sayyiduna Jabir (may Allah be pleased with him) narrates: On the day of the expedition of Ta'if, the Prophet (peace and blessings be upon him) stood with Sayyiduna Ali (may Allah be pleased with him) for a large part of the day. Abu Bakr (may Allah be pleased with him) said to him (peace and blessings be upon him): O Messenger of Allah, today you have conversed privately with Ali (may Allah be pleased with him) for a very long time. The Messenger of Allah (peace and blessings be upon him) said: "It was not I who conversed privately with him; rather, it was Allah who conversed privately with him."
Hadith Referenceالمعجم الكبير للطبراني / باب الجيم / 1743