The Messenger of Allah ﷺ said, "The night prayer is performed in pairs of two, and the witr is a single rakah."
أخبرنا قتيبة قال حدثنا خالد بن زياد عن نافع
قال رسول الله ﷺ صلاة الليل مثنى مثنى والوتر ركعة واحدة
Its isnad is sahih, and it is agreed upon, as previously mentioned, hadith no. 1672, and it is also in Kubra, hadith no. 474.