From Sahih Muslim (Hadith 6990):
Abu Musa reported Allah's Messenger (ﷺ) as saying that Allah, the Exalted and Glorious, Stretches out His Hand during the night so that the people may repent for the fault committed from dawn till dusk and He stretches out His Hand during the day so that the people may repent for the fault committed from dusk to dawn. (He would accept repentance) before the sun rises in the west (before the Day of Resurrection). A hadith like this has been narrated on the authority of Shu'ba with the same chain of transmitters
Reference: Muslim 6990