Musnad Abu Ya'la al-Mawsili 115:69

Zakariya ibn Yahya narrated to us, Khalid narrated to us, from Sa'id, from Qatadah, from Anas, that the Messenger of Allah (ﷺ) was upon Uhud, and Abu Bakr, Umar, and Uthman were with him. It shook beneath them, so he struck it with his foot and said: "Be firm, Uhud! For upon you is a Prophet, a Siddiq, and two martyrs."