It is reported that 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 disbelievers" [Kafirun 109:1], and "Say, He is Allah, the One" [Ikhlas 112:1]. When he gave the closing salutation, he would say, "Glory be to the King, the Most Holy," repeating it three times.
حدثنا أبو داود حدثنا شعبة أخبرنا قتادة قال سمعت زرارة يحدث
ى أن رسول الله ﷺ كان يوتر بسبح اسم ربك الأعلى وقل يا أيها الكافرون وقل هو الله أحد فإذا سلم قال سبحان الملك القدوس يقولها ثلاثا
Its isnad is sahih, and Zurara should correctly be Azra, as mentioned previously, and the hadith has already appeared at 15290.