Sayyiduna Amir bin Rabi'ah (may Allah be pleased with him) narrates: I went out with the Prophet (peace and blessings be upon him) to go to the mosque, and his sandal strap broke. I took his strap so that I could fix it, but he took it from my hand and said: "This is preferential treatment, and I do not like preferential treatment."
Al-Bazzar recorded it; its chain contains a narrator whom I do not know.