Sunan Abi Dawud Book 5, Hadith 66
The Messenger of Allah (ﷺ) as saying: Our Lord who is blessed and exalted descends every night to the lowest heaven when the last one-third of the night remains, and says: Who supplicated Me so that I may answer him ? Who asks of Me so that I may give to him ? Who asks My forgiveness so that I may forgive him ?
The Prophet (ﷺ) said: Any person who offers prayer at night regularly but (on a certain night) he is dominated by sleep will be given the reward of praying. His sleep will be almsgiving.
Allah, the Exalted, would awaken the Messenger of Allah (ﷺ) at night. When the dawn came, he would his finish daily round of recital.