Sunan an-Nasa'i

Zuhair narrated from Abu Ishaq, from Sa'eed bin Jubair, : Ibn Abbas used to pray witr with three (units) with (the Surahs): "Glorify the Name of Your Lord, the Most High" (Surah Al-A'la), "Say: O You disbelievers" (Surah Al-Kafirun), and "Say: He is Allah, (the) One" (Surah Al-Ikhlas).