Sahih Muslim Book 1, Hadith Number 385.

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 Huraira reported: Verity the Messenger of Allah (may peace be upon him) said: There is for every apostle a (special) prayer with which he would pray. I wish I could reserve, my prayer for intercession of my Ummah on the Day of Resurrection.