Musannaf Ibn Abi Shayba 22:188

Yazid ibn Harun narrated to us, he said: Ibn 'Awn informed us, from Ibn Sirin, who said: I asked 'Ubaydah about a verse in the Book of Allah. He said: "You must have taqwa (fear/consciousness) of Allah and be upright (al-sadad), for those who knew about what the Quran was revealed have passed away."