Musannaf Ibn Abi Shayba 33:168

'Affan narrated to us, he said: Shu'bah narrated to us, he said: Musa ibn Anas narrated to me, he said: I heard Anas saying: "Indeed, the Messenger of Allah (peace and blessings of Allah be upon him) said: 'If you knew what I know, you would laugh little and weep much.'"