In the mosque of Kufa, he said, "By Allah, I remember when Umar had me bound captive for embracing Islam, before Umar himself became a Muslim. If the mountain of Uhud were to crumble apart over what you did to Uthman, it would be justified."
في مسجد الكوفة: والله لقد رأيتني وإن عمر لموثقي على الإسلام قبل أن يسلم عمر، ولو أن أحدا ارفض للذي صنعتم بعثمان لكان.
Bukhari narrated it in the Merits of the Ansar (3862) from Qutayba bin Saeed, who said, Sufyan told us, from Ismail, from Qays, who said, I heard Saeed bin Zayd bin Amr bin Nufayl saying, in the masjid of Kufa, and he mentioned it.In another wording, "If you had seen me binding Umar for the sake of Islam, myself and his sister, before he became Muslim. And if Mount Uhud were to crumble because of what you did to Uthman, it would be justified in crumbling."Bukhari narrated it (3867) through another route, from Ismail, from Qays, and he mentioned it.