Sahih Bukhari Volume 005, Book 057, Hadith Number 024.
Narated By Anas bin Malik : The Prophet once climbed the mountain of Uhud with Abu Bakr, 'Umar and 'Uthman. The mountain shook with them. The Prophet said (to the mountain), "Be firm, O Uhud! For on you there are no more than a Prophet, a Siddiq and two martyrs.