It is narrated from Sayyiduna al-Harith bin al-Simmah (may Allah be pleased with him) that he said: "I met the Messenger of Allah (peace and blessings be upon him) when he (peace and blessings be upon him) had come out after relieving himself. I greeted him (peace and blessings be upon him) with salam, but he (peace and blessings be upon him) did not reply to me until he (peace and blessings be upon him) placed his hand on a wall and wiped his face and hands; then he returned my greeting."
Only Sa'id bin Abi Ayyub (may Allah have mercy on him) narrated this hadith from Ubaydullah bin Abi Ja'far (may Allah have mercy on him), and Rawh bin Salah (may Allah have mercy on him) is alone in narrating it.