It wasnarrated from Abu Ayyub Al-Ansari that the Messenger of Allah(ﷺ)said:
"Witr is Haqq.* Whoever wishes let him pray Witr with five(Rak'ah), and whoever wishes let him pray Witr with three (Rak'ah),and whoever wishes let him pray Witr with one (Rak'ah)." (TH)
English reference (TH): Vol. 1, Book 5, Hadith 1190 (TH)
Arabic reference (TH): Book 5, Hadith 1246 (TH)