From Sahih Bukhari (Hadith 3686):
Narrated Anas bin Malik:The Prophet (ﷺ) ascended the mountain of Uhud and he was accompanied by Abu Bakr, `Umar and `Uthman. The mountain shook beneath them. The Prophet (ﷺ) 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)
Reference: Bukhari 3686