Musannaf Ibn Abi Shayba 22:189

Ghundar narrated to us, from Shu'bah, from 'Amr ibn Murrah, who said: A man asked Sa'id ibn al-Musayyib about a verse of the Qur'an. He said: "Do not ask me about the Qur'an, and ask about it the one who claims that nothing of it is hidden from him," meaning 'Ikrimah.