It was narrated that 'Uqbah bin 'Amir said: "I came to the Messenger of Allah (ﷺ) while he was riding, and I put my hand on his foot and said: 'Teach me Surah Hud, teach me Surah Yusuf. He said: 'You will never recite anything more precious before Allah, the Mighty and Sublime, than: 'Say: I seek refuge with (Allah) the Lord of the daybreak.'"
Source: sunnah.com
Other translations
Arabic
أَخْبَرَنَا قُتَيْبَةُ، قَالَ حَدَّثَنَا اللَّيْثُ، عَنْ يَزِيدَ بْنِ أَبِي حَبِيبٍ، عَنْ أَبِي عِمْرَانَ، أَسْلَمَ عَنْ عُقْبَةَ بْنِ عَامِرٍ، قَالَ أَتَيْتُ رَسُولَ اللَّهِ صلى الله عليه وسلم وَهُوَ رَاكِبٌ فَوَضَعْتُ يَدِي عَلَى قَدَمِهِ فَقُلْتُ أَقْرِئْنِي سُورَةَ هُودٍ أَقْرِئْنِي سُورَةَ يُوسُفَ . فَقَالَ " لَنْ تَقْرَأَ شَيْئًا أَبْلَغَ عِنْدَ اللَّهِ عَزَّ وَجَلَّ مِنْ { قُلْ أَعُوذُ بِرَبِّ الْفَلَقِ } " .
sunnah.com