Musnad Ahmad 1139:3

Ya'qub narrated to us, my father narrated to us, from Muhammad ibn Ishaq, 'Abd al-Rahman ibn Hurmuz al-A'raj narrated to me, from 'Umayr, the freed slave of 'Abd Allah ibn 'Abbas—and 'Umayr, the freed slave of 'Abd Allah ibn 'Abbas, was trustworthy according to what has reached me—from Abu Juhaym ibn al-Harith ibn al-Simma al-Ansari, who said: The Messenger of Allah (may Allah bless him and grant him peace) went out for some need of his toward Bi'r Jamal. Then he approached, and a man from his companions met him and greeted him with peace. The Messenger of Allah (may Allah bless him and grant him peace) did not return the greeting to him until he placed his hand on a wall, then wiped his face and his hands, and then said: "And upon you be peace."