Sunan an-Nasa'i, Volume 6, Book 50, Hadith 5442 (DarusSalam) ⓘ
It was narrated from 'Uqbah bin 'Amir that: The Prophet [SAW] said: "There have been revealed to me Verses the like of which has never been seen: 'Say: I seek refuge with (Allah) the Lord of the daybreak...' to the end of the Surah, and 'Say: I seek refuge with (Allah) the Lord of mankind...' to the end of the Surah."
أَخْبَرَنَا مُحَمَّدُ بْنُ الْمُثَنَّى، قَالَ حَدَّثَنَا يَحْيَى، قَالَ حَدَّثَنَا إِسْمَاعِيلُ، قَالَ حَدَّثَنَا قَيْسٌ، عَنْ عُقْبَةَ بْنِ عَامِرٍ، عَنِ النَّبِيِّ صلى الله عليه وسلم قَالَ " أُنْزِلَ عَلَىَّ آيَاتٌ لَمْ يُرَ مِثْلُهُنَّ { قُلْ أَعُوذُ بِرَبِّ الْفَلَقِ } إِلَى آخِرِ السُّورَةِ وَ { قُلْ أَعُوذُ بِرَبِّ النَّاسِ } " . إِلَى آخِرِ السُّورَةِ .
also referenced under: Hadith 5440 (Reference) & Book 50, Hadith 13 (In-Book)