Musannaf Ibn Abi Shayba 27:234

Yahya ibn Abi Bukayr narrated to us, he said: Shu'bah narrated to us, from Ibn Abi Najih, from Mujahid, from Ibn Abbas, who said: "Isa, peace be upon him, did not speak except with the signs (ayat) with which he spoke, until he reached the age of children."