Ibn 'Umar said:He who prayed at night should make Witr the end of his prayer, for the Messenger of Allah (ﷺ) ordered this

Ibn 'Umar reported Allah's Messenger (ﷺ) as saying:Make Witr the end of your night prayer

Nafi' reported Ibn 'Umar as saying:He who observed the night prayer should make Witr the end of his prayer before dawn. The Messenger of Allah (ﷺ) used to order them thus