The Messenger of Allah ﷺ used to perform the Witr prayer reciting "Glorify the name of your Lord, the Most High" [Ala 87:1], "Say, O you disbelievers" [Kafirun 109:1], and "Say, He is Allah, the One" [Ikhlas 112:1].
حدثنا عثمان بن أبي شيبة حدثنا أبو حفص الأبار حدثنا الأعمش عن طلحة وزبيد عن ذر عن سعيد بن عبد الرحمن بن أبزى عن أبيه
كان رسول الله ﷺ يوتر بسبح اسم ربك الأعلى وقل يا أيها الكافرون وقل هو الله أحد
[Sahih] Reported by Abu Dawud, Witr, chapter on what is recited in Witr, no. 1423, from Uthman (and others), through this route. Amash used the vague form "ana" in his transmission. Daraqutni reported it, 2/31, with a hasan chain of transmission, from Fitr, from Zubayd, from Saeed, through this route, and its chain of transmission is strong. The hadith has other routes of transmission as well, and Ibn Hibban graded it sahih.