(a) Uqbah bin Amir al-Juhani (may Allah be pleased with him) said that the Messenger of Allah (peace and blessings be upon him) said: "Some verses have been revealed to me the like of which no one has seen," meaning the Mu'awwidhatayn.
(b) The wording of the narration of Muhammad bin Ubayd (may Allah have mercy on him) is: "Tonight some verses were revealed to me the like of which I have not seen; they are the Mu'awwidhatayn."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الصلاة / 4046