(45) باب الْوِتْرِ بِثَلاَثَ عَشْرَةَ رَكْعَةً
It was narrated that Umm Salamah said:
"The Messenger of Allah (ﷺ) used to pray witr with thirteen rak'ahs, but when he grew older and weaker he prayed witr with nine." (JA)
Reference (JA): Sunan an-Nasa'i 1727 (JA)
In-book reference (JA): Book 20, Hadith 130 (JA)
English translation (JA): Vol. 2, Book 20, Hadith 1728 (JA)