Sunan an-Nasa'i · Hadith 1682
The Book of Qiyam Al-Lail (The Night Prayer) and Voluntary Prayers During the Day - كتاب قيام الليل وتطوع النهار
أخبرنا قتيبة، قال حدثنا الليث، عن نافع، أن ابن عمر، قال من صلى من الليل فليجعل آخر صلاته وترا فإن رسول الله صلى الله عليه وسلم كان يأمر بذلك .
It was narrated that Ibn 'Umar said: "Whoever prays during the night, let him make the last of his prayers at night witr, because the Messenger of Allah (ﷺ) used to enjoin that."
Gradings are classical jarḥ-wa-taʿdīl, name-matched to a rijāl index (not individually re-verified).