Musannaf Ibn Abi Shayba 3:3093

Mu'awiyah ibn Hisham narrated to us, he said: Sulayman ibn Qarm narrated to us, from Abu Habib, from a man (Nabil), from Salamah bint Af'a, she said: I was with Aisha among a group of women, and I heard her saying: "Indeed, the day of Friday is like the day of Arafah, and there is an hour in it during which the gate of mercy is opened." We said: "Which hour is it?" She said: "When the caller calls for the prayer."