Musnad Ahmad 482:79

'Affan narrated to us, Abu 'Awanah narrated to us, from Bayan, from Qays ibn Abi Hazim, 'Uqbah ibn 'Amir al-Juhani narrated to us, he said: The Messenger of Allah (peace and blessings of Allah be upon him) said: "Have you not seen verses that were revealed tonight, the likes of which have not been seen—or: are not seen—: the two refuge-seeking surahs (al-Mu'awwidhatayn)?"