Musannaf Ibn Abi Shayba 34:123

Shadhan narrated to us, Jarir ibn Hazim narrated to us, he said: Zubayd ibn al-Harith narrated to us, from Ikrimah, from Ka’b, who said: The first of what was revealed of the Quran from the Torah was ten verses, and they are the ten which were revealed at the end of Surat al-An’am.