Musnad Ahmad 32:865

Muhammad narrated to us, he said: Shu'bah and Yazid narrated to us, he said: Shu'bah informed us, from Qatadah, from Anas ibn Malik, that the Messenger of Allah, may Allah bless him and grant him peace, said: "Were it not that you would not bury one another, I would have supplicated to Allah to let you hear the punishment of the grave."