Musnad Ahmad 30:596

'Abd al-Razzaq narrated to us, Ma'mar narrated to us, from al-Zuhri, who said: al-Qasim ibn Muhammad informed me, saying: Abu Hurayrah and Ka'b gathered. Abu Hurayrah began narrating to Ka'b from the Prophet, may God bless him and grant him peace, and Ka'b began narrating to Abu Hurayrah from the Books. Abu Hurayrah said: The Prophet, may God bless him and grant him peace, said: "For every prophet there is a supplication that is answered, and I have reserved my supplication as an intercession for my nation on the Day of Resurrection."