Musnad Ahmad 33:82

Muhammad ibn Ja'far narrated to us, Shu'bah narrated to us, from al-Aswad ibn Qays, from Nabih al-'Anazi, from Jabir ibn 'Abdullah, who said: The Messenger of Allah (peace and blessings of Allah be upon him) said: "If you enter at night, let none of you come to his family unexpectedly (at night)." Jabir said: "By Allah, we did come to them unexpectedly after that."