Musnad Ahmad 32:1535

Ya'qub narrated to us, my father narrated to me, from Salih, Ibn Shihab said: Anas ibn Malik informed me: "That Allah, the Mighty and Majestic, continued the revelation upon the Messenger of Allah, may Allah bless him and grant him peace, before his death until he passed away. The revelation was at its most frequent on the day the Messenger of Allah, may Allah bless him and grant him peace, passed away."