Sahih Muslim | Book 1 | Hadith Number 392

Narrated by Anas b. Malik
Anas b. Malik reported: Verily the Apostle of Allah (may peace be upon him) said: There is for every apostle a prayer with which he prays (to Allah) for his Ummah. I have reserved my prayer for the intercession of my Ummah on the Day of Resurrection.