Musnad Abu Ya'la al-Mawsili 108:81

Zuhayr narrated to us, Hushaym narrated to us, Abu al-Zubayr narrated to us, from Jabir, who said: The Messenger of Allah (may Allah bless him and grant him peace) said: "Beware, let no man spend the night with a woman in a house, unless he is a husband or a mahram (a prohibited relative)."