Musnad Abu Ya'la al-Mawsili 115:356

Ubayd Allah narrated to us, Khalid and Yazid ibn Zuray' narrated to us, they said: Sa'id narrated to us, Qatadah narrated to us, from Anas: That the Messenger of Allah (may Allah bless him and grant him peace) ascended Mount Uhud, and with him were Abu Bakr, Umar, and Uthman. The mountain shook beneath them. In the narration of Yazid, he struck it with his foot and said: "Be firm, Uhud, for upon you there is a Prophet, a Siddiq (truthful one), and two martyrs."