I followed the Messenger of Allah ﷺ while he was riding. I placed my hand on his foot and said, "Recite to me from Surah Yusuf."He replied, "You will not recite anything more powerful before Allah than 'Say, I seek refuge in the Lord of the daybreak' [Falaq 113:1]."
حدثنا هاشم حدثنا ليث حدثني يزيد بن أبي حبيب عن أبي عمران أسلم
اتبعت رسول الله ﷺ وهو راكب فوضعت يدي على قدميه فقلت أقرئني من سورة يوسف فقال لن تقرأ شيئا أبلغ عند الله عز وجل من قل أعوذ برب الفلق
Its isnad is sahih, but the isnad contains an error. A mistake occurred between Yazid bin Abu Habib and Abu Imran, which is a slip by the copyists. Nasai narrated it in the correct form, Yazid from Abu Imran, 2/158, in the chapter on the Opening, the excellence of reciting the two Muawwidhatayn. The hadith has already been given in similar form at 17235.