I heard Saeed bin Zayd bin Amr bin Nufayl say in the mosque of Kufa, "By Allah, I remember when Umar had me bound up because of my acceptance of Islam, before he himself became Muslim. And if Mount Uhud were to crumble apart over what you have done to Uthman, it would have every right to do so."
سمعت سعيد بن زيد بن عمرو بن نفيل يقول في مسجد الكوفة: والله لقد رأيتني وإن عمر لموثقي على الاسلام قبل ان يسلم، ولو ان احدا ارفض للذي صنعتم بعثمان لكان.
Bukhari narrated it in the Virtues 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 then he mentioned it.In another wording, "If you had seen me binding Umar for the sake of Islam, myself and his sister, before he had embraced Islam. And if a mountain were to crumble on account of what you did to Uthman, it would be justified in crumbling." Bukhari narrated it (3867) through another route from Ismail, from Qays, and then he mentioned it.