Musnad Ahmad 1153:332

Waki’ narrated to us, Abu Ja’far al-Razi narrated to us, from Muhammad ibn al-Munkadir, from Sa’id ibn Jubayr, from ‘Aishah, who said: The Messenger of Allah (peace and blessings of Allah be upon him) said: "There is no man who has a time of the night in which he stands [to pray], but he sleeps through it, except that the reward of his prayer is written for him, and his sleep is a charity that was given to him."