Yahya related to me from Malik from Muhammad ibn al-Munkadir fromSaid ibn al-Jubayr that a man who has approval (as a relater ofhadith), told him that A'isha, the wife of the Prophet, may Allahbless him and grant him peace, said, "If a man prays in the night andsleep overcomes him during it, Allah writes for him the reward of hisprayer, and his sleep is sadaqa for him."
App reference: Book 7, Hadith 1
USC-MSA web (English) reference: Book 7, Hadith 1
Arabic reference: Book 7, Hadith 255