Sahih Muslim
The Book of Faith (Kitab Al-Iman)
Book Number: 001 / Hadith Number: 396
Abu Zubair heard Jabir b. Abdullah reporting it from the Apostle of Allah (may peace be upon him): For every apostle was a prayer with which he prayed (to his Lord) for his Ummah, but I have reserved my prayer for the intercession of my Ummah on the Day of Resurrection.