Musnad Ahmad 928:5

Muhammad ibn Ja‘far narrated to us, Shu‘bah narrated to us, from ‘Asim ibn Bahdalah, from Zirr, who said: I asked Ubayy about the *Mu‘awwidhatayn* (the two surahs of seeking refuge). He said: "I asked the Messenger of Allah, peace and blessings of Allah be upon him, about them." He said: "So it was said to me, and I said." Then the Messenger of Allah, peace and blessings of Allah be upon him, commanded us, and we say [them].