Musnad Abu Ya'la al-Mawsili 110:175

Masruq ibn al-Marzuban narrated to us, Ibn Abi Za'idah narrated to us, he said: Dawud ibn Abi Hind narrated to me, from 'Ikrimah, from Ibn 'Abbas, who said: Quraysh said to the Jews, "Give us something to ask this man about." They said, "Ask him about the Spirit (al-Ruh)." So they asked him, and [the verse] was revealed: "And they ask you about the Spirit. Say, 'The Spirit is of the affair of my Lord, and you have not been given of knowledge except a little'" (Al-Isra: 85). They said, "We have not been given of knowledge except a little, yet we have been given the Torah, and whoever is given the Torah has been given much good." So [the verse] was revealed: "Say, 'If the sea were ink for the words of my Lord...'" (Al-Kahf: 109).