Musnad Ahmad 1153:1154

'Abd al-Razzaq and Muhammad ibn Bakr narrated to us, they said: Ibn Jurayj informed us, al-Mughirah ibn Hakim informed me, from Umm Kulthum bint Abi Bakr, that she informed him, from 'Aishah, she said: The Prophet, peace and blessings of Allah be upon him, delayed [the prayer] one night until most of the night had passed, and until the people of the mosque had slept—and Ibn Bakr said: "had slumbered"—then he went out and prayed. He said: "It is its time, were it not for the fact that it would be difficult for my nation." And Ibn Bakr said: "that I would make it difficult."