Musannaf Ibn Abi Shayba 3:1161

Abu Khalid al-Ahmar narrated to us, from Mujalid, from Abu al-Wadak, from Abu Sa’id, who said: The Messenger of Allah (peace and blessings of Allah be upon him) said: "Allah laughs at three: the people when they stand in rows for prayer, the man who fights behind his companions, and the man who stands up in the darkness of the night."