The Messenger of Allah ﷺ said, "Allah waits until the first third of the night has passed, then He descends to the lowest heaven and says, 'Is there anyone seeking forgiveness? Is there anyone repenting? Is there anyone asking? Is there anyone calling upon Me?' This continues until dawn breaks."
قال رسول الله ﷺ: إن الله يمهل حتى إذا ذهب ثلث الليل الأول نزل إلى السماء الدنيا، فيقول: هل من مستغفر؟ هل من تائب؟ هل من سائل؟ هل من داع؟ حتى ينفجر الفجر.
Muslim narrated it in the Book of the Prayer of Travelers (758:172), through various routes from Jareer, from Mansur, from Abu Ishaq, from Aghar Abu Muslim, who narrated it from Abu Saeed and Abu Hurairah, who both mentioned it.