Musnad Abu Ya'la al-Mawsili 42:207

Zuhayr narrated to us, Jarir narrated to us, from Mansur, from Abu Ishaq, from al-Agharr Abu Muslim, who narrates it from Abu Sa’id al-Khudri and from Abu Hurayrah, they said: The Messenger of Allah (may Allah bless him and grant him peace) said: "Indeed, He grants respite until, when the first third of the night has passed, He—Blessed and Exalted is He—descends to the lowest heaven. Then He says: 'Is there anyone seeking forgiveness? Is there anyone asking? Is there anyone supplicating?' until the dawn breaks."