Musannaf Ibn Abi Shayba 3:6328

Waki’ narrated to us, from Sufyan, from Abdullah ibn al-Sa’ib, from Zadhan, from Abdullah, who said: The Messenger of Allah (peace and blessings of Allah be upon him) said: "Indeed, Allah has angels who travel about the earth; they convey to me the greeting (salam) from my Ummah."