Musannaf Ibn Abi Shayba 38:20

Muhammad ibn Bishr narrated to us, he said: I heard Ahmad ibn Abdullah ibn al-Asamm mentioning from Umm Rashid, his grandmother, who said: I was with Umm Hani when Ali came to her, so she called for food for him. He said, "Why do I not see a blessing with you?" meaning the sheep. She said: I said, "Subhan Allah! Yes, by Allah, we indeed have a blessing." He said, "I only meant the sheep." She said: I went down and met two men on the stairs, and I heard one of them saying to his companion, "Our hands have pledged allegiance to him, but our hearts have not pledged allegiance to him." She said: I said, "Who are these two men?" They said, "Talha and al-Zubayr." She said: I said, "I have heard one of them saying to his companion, 'Our hands have pledged allegiance to him, but our hearts have not pledged allegiance to him.'" Ali said: "Whoever breaks his pledge, he only breaks it against his own soul, and whoever fulfills what he has covenanted with Allah, He will give him a great reward."