The Messenger of Allah ﷺ said, "Two surahs have been revealed to me, so seek refuge with them, for nothing like them has ever been used to seek refuge," meaning the Muawwidhatayn.
حدثنا حفص بن غياث عن إسماعيل عن قيس
قال رسول الله ﷺ أنزلت علي سورتان فتعوذوا بهن فإنه لم يتعوذ بمثلهن يعني المعوذتين
No references are available.
Its isnad is sahih. Its narrators are well-known and trustworthy. Ismail is Ibn Abu Khalid, and Qays is Ibn Abu Hazim. The hadith was mentioned previously at 17230, and it is found in Muslim, 1/558, no. 814.