From Sahih Bukhari (Hadith 6942):
Narrated Qais:I heard Sa`id bin Zaid saying, "I have seen myself tied and forced by `Umar to leave Islam (Before `Umar himself embraced Islam). And if the mountain of Uhud were to collapse for the evil which you people had done to `Uthman, then Uhud would have the right to do so." (See Hadith No. 202, Vol)
Reference: Bukhari 6942