Sahih Muslim Book 7, Hadith Number 3126.

Chapter : The merit of Hajj and Umra and the day of ‘Arafa (the 9th of Dhu’l-Hijja).

‘Aisha (Allah be pleased with her) reported Allah’s Messenger (may peace be upon him) as saying: There is no day when God sets free more servants from Hell than the Day of ‘Arafa. He draws near, then praises them to the angels, saying: What do these want?