Sahih Muslim
The Book of Faith (Kitab Al-Iman)
Book Number: 001 / Hadith Number: 388
Amr b. Abu Sufyan reported: Abu Huraira said to Ka'b al-Ahbar that the Apostle of Allah (may peace be upon him) had said: For every apostle there Is a (special) prayer by which he would pray (to his Lord). I, however, intend (if Allah so willed) that I would reserve my prayer for the intercession of my Ummah on the Day of Resurrection. Ka'b said to Abu Huraira: Did you hear this from the Messenger of Allah (may peace be upon him)? Abu Huraira said: Yes.