Sahih Bukhari Volume 005, Book 057, Hadith Number 035.
Narated By Anas bin Malik : The Prophet ascended the mountain of Uhud and he was accompanied by Abu Bakr, 'Umar and 'Uthman. The mountain shook beneath them. The Prophet hit it with his foot and said, "O Uhud ! Be firm, for on you there is none but a Prophet, a Siddiq and a martyr (i.e. and two martyrs).