Musnad Ahmad — Hadith 24009/61

Yaqoob narrated to us, my father narrated to us, from Muhammad ibn Ishaq, he told me from Abdur Rahman ibn Hurmuz al-A'raj, from Umair, the freed slave of Abdullah ibn Abbas—and Umair, the freed slave of Abdullah ibn Abbas, was trustworthy as has reached me—from Abu Juhaim ibn al-Harith ibn al-Simmah al-Ansari, who said:

The Messenger of Allah, peace and blessings be upon him, went out for some of his needs toward the well of Jamal, then he returned, and a man from his companions met him and greeted him with salam, but the Messenger of Allah, peace and blessings be upon him, did not return the greeting to him until he placed his hand on the wall, then wiped his face and his hands, then said: "And upon you be peace."