Musnad Ahmad 28:268

Hassan narrated to us, Ibn Lahi'ah narrated to us, Bakr ibn Sawadah narrated to us, from Abd al-Rahman ibn Jubayr, that Abdullah ibn Amr narrated to him: That a group of the Banu Hashim entered upon Asma bint Umays. Abu Bakr entered, and she was his wife at that time. He saw them and disliked that. He mentioned that to the Messenger of Allah (peace and blessings of Allah be upon him) and said: "I did not see anything but good." The Messenger of Allah (peace and blessings of Allah be upon him) said: "Indeed, Allah has declared her innocent of that." Then the Messenger of Allah (peace and blessings of Allah be upon him) stood upon the pulpit and said: "Let no man enter after this day of mine upon a woman whose husband is absent, unless he is with one or two men."