Musannaf Ibn Abi Shayba 37:609

Abu Bakr narrated to us, he said: Muhammad bin Bishr narrated to us, he said: Isma'il bin Abi Khalid narrated to us, from Mujalid, from al-Sha'bi, from 'Amir bin Shahr, who said: I heard a word from the Prophet, may Allah bless him and grant him peace, and a word from the Negus. I heard the Prophet, may Allah bless him and grant him peace, saying: "Observe the Quraysh, listen to their speech, and leave their actions." He said: And I was with the Negus when a son of his came with a book, and he read a verse from the Gospel, and I understood it, so I laughed. He said: "What are you laughing at? At the Book of Allah? By Allah, it is indeed in the Book of Allah which was revealed to Jesus that the curse shall be upon the earth when its rulers are children."