Musnad Ahmad 32:1129

Yazid ibn Harun narrated to us, Humaid informed us, from Anas, who said: "The Messenger of Allah (peace and blessings of Allah be upon him) held a wedding feast for Zaynab, and he fed the Muslims until they were full with bread and meat. Then he went out as he used to do when he married, so he would come to the chambers of the Mothers of the Believers, and he would greet them, and pray for them, and they would greet him, and pray for him. Then he returned, and I was with him. When he reached the door, there were two men who had been talking to each other in a corner of the house. When the Messenger of Allah (peace and blessings of Allah be upon him) saw them, he turned away. When the two men saw that the Prophet (peace and blessings of Allah be upon him) had returned, they jumped up in alarm and left. I do not know whether I informed him or someone else informed him, but the Prophet (peace and blessings of Allah be upon him) returned."