Musannaf Ibn Abi Shaybah

Hazrat Aisha (may Allah be pleased with her) says that the day of Friday is like the day of Arafah; in it, there is an hour during which the doors of mercy are opened. In it, there is an hour such that whatever a servant asks from Allah Almighty, it is granted to him. Hazrat Aisha (may Allah be pleased with her) was asked which hour that is. She replied: When the muezzin gives the call to the Fajr prayer.