Musnad Ahmad 28:359

Muhammad ibn Ja‘far narrated to us, Shu‘bah narrated to us, from al-Hakam, who said: I heard Sayf narrating from Rashid al-Hajari, from his father: That a man said to ‘Abdullah ibn ‘Amr: "Narrate to me what you heard from the Messenger of Allah (may Allah bless him and grant him peace), and leave me be regarding what you found in your saddlebags on the day of Yarmouk." He said: I heard the Messenger of Allah (may Allah bless him and grant him peace) saying: "The Muslim is the one from whose tongue and hand the Muslims are safe."