Sahih Muslim Book 1, Hadith Number 396.

Chapter : Pertaining to the words of the Apostle of Allah (may peace be upon him): “I would be the first among people to Intercede in the Paradise and among the Apostles I would have the largest following”.

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.