Bulugh al-Maram: The Book of Prayer – Hadith No. 457 — And in another narration of al-Bukhari and Muslim, narrated: “He used to pray… (Hadith No. 457)

And in another narration of al-Bukhari and Muslim, narrated: "He used to pray ten Rak'at (of prayer), and making it Witr by one Rak'at, and he used to pray the two (Sunnah) Rak'at of Fajr, so that it became thirteen Rak'at."

Explanation:

Reference: Bulugh al-Maram, The Book of Prayer, Hadith No. 457