Narrated Abu Sahlah:
"The day of the house (when he was besieged), 'Uthman said: 'Indeed the Messenger of Allah (ﷺ) took a covenant from me, and I will abide by it.'" (ID)
English reference (ID): Vol. 1, Book 46, Hadith 3711 (ID)
Arabic reference (ID): Book 49, Hadith 4076 (ID)