Musnad Abu Ya'la al-Mawsili 115:181

Abu Musa narrated to us, Mu'adh ibn Hisham narrated to us, my father narrated to me, from Qatadah, Anas ibn Malik narrated to us that the Messenger of Allah (may Allah bless him and grant him peace) said: "Indeed, for every prophet there is a supplication with which he supplicated for his nation, and I have reserved my supplication as an intercession for my nation on the Day of Resurrection."