The Prophet ﷺ said, "Make the last of your prayers at night the witr."
حدثنا يحيى عن عبيد الله حدثني نافع
عن النبي ﷺ قال اجعلوا آخر صلاتكم بالليل وترا
Its isnad is sahih. Abu Dawud (1:450) also narrated it from Ahmad bin Hanbal with this same isnad. Munziri said (1388), Bukhari and Muslim also narrated it. See 4571.