“How should I perform Witr?” He said: “Pray Witr with one Rak’ah.” He said: “I am afraid that the people will say that I am cutting the prayer short.” He said: “The Sunnah of Allah and His Messenger.” Meaning “This is the Sunnah of Allah and His Messenger.”
Sunan Ibn Majah Book 5, Hadith 374
← Previous Hadith “The Messenger of Allah (ﷺ) said: ‘Night prayers are to be offered two by two, and Witr is one Rak’ah.’ I said: ‘What do you think if I become drowsy and I want to sleep?’ He said: ‘Put “what do you think” up there with that star? (i.e., don’t think about it at all).’ I raised my head and saw As- Simak.* He repeated that the Messenger of Allah (ﷺ) said, ‘Night prayers are to be offered two by two, and Witr is one Rak’ah, before dawn.’”

* Here, As-Simak refers to a star or stars, either Arcturus (As-Simak Ar-Ramih) or Spica, also called Alpha Virginis (As-Simak Al-A'zal).

Sunan Ibn Majah Book 5, Hadith 373 Next Hadith → “The Messenger of Allah (ﷺ) used to say Taslim after every two Rak’ah, and he would perform Witr with one Rak’ah.”

Sunan Ibn Majah Book 5, Hadith 375