Musnad Ahmad 32:779

Hajjaj narrated to us, he said: Shu'bah narrated to me, he said: I heard Qatadah, Anas ibn Malik narrated to us, that the Messenger of Allah, peace and blessings of Allah be upon him, used to say: "Indeed, the good is the good of the Hereafter," or he said: "O Allah, there is no good except the good of the Hereafter, so forgive the Ansar and the Muhajirun." Shu'bah said: "And Qatadah used to say this in his stories."