Musnad Ahmad 928:3

'Abd al-Rahman ibn Mahdi narrated to us, Sufyan narrated to us, from 'Asim, from Zirr, who said: Ubayy ibn Ka'b narrated to me, saying: I asked the Messenger of Allah, may Allah bless him and grant him peace, about the two refuge-seeking surahs (al-Mu'awwidhatayn). He said: "It was said to me, so I said." Ubayy said: So the Messenger of Allah, may Allah bless him and grant him peace, said [it] to us, and we say [it].