The Messenger of Allah ﷺ used to observe witr with (reciting) "Glorify the name of thy Lord, the most High" (Surah 87), "Say O disbelievers" (Surah 109), and "Say, He is Allah, the One, Allah, the eternally besought of all" (112).
كَانَ رَسُولُ اللَّهِ ﷺ يُوتِرُ بِ { سَبِّحِ اسْمَ رَبِّكَ الأَعْلَى } وَ { قُلْ لِلَّذِينَ كَفَرُوا } وَاللَّهُ الْوَاحِدُ الصَّمَدُ