Sayyiduna Abdullah bin Abbas (may Allah be pleased with them both) said that the Messenger of Allah (peace and blessings be upon him) used to recite in witr "Glorify the name of your Lord, the Most High" [Surah al-A'la: 1], "Say: O disbelievers" [Surah al-Kafirun: 1] and "Say: He is Allah, the One" [Surah al-Ikhlas: 1].
(b) In the narration of Isra'il the wording differs somewhat: that the Messenger of Allah (peace and blessings be upon him) used to pray witr.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الصلاة / 4857