Musnad Ahmad 30:3342

Hajjaj narrated to us, Ibn Jurayj informed us, Al-Ala’ ibn Abd al-Rahman ibn Ya’qub narrated to me, from Ibn Darah, the freed slave of Uthman, who said: We were at Al-Baqi’ with Abu Hurayrah when we heard him say: "I am the most knowledgeable of people regarding the intercession of Muhammad, may Allah bless him and grant him peace, on the Day of Resurrection." He said: The people crowded around him and said: "Tell us, may Allah have mercy on you." He said: He says: "O Allah, forgive every Muslim servant who met You believing in me and not associating anything with You."