Musnad Abu Ya'la al-Mawsili 151:84

Sa'id ibn al-Ash'ath narrated to us, 'Abd al-Malik ibn al-Walid ibn Ma'dan informed me, 'Asim narrated to us, from Zirr, from 'Abdullah ibn Mas'ud, who said: The Messenger of Allah (may Allah bless him and grant him peace) used to recite in the Witr prayer: in the first rak'ah, "Glorify the name of your Lord, the Most High" (Sabbih isma rabbika al-a'la); In the second, "Say, 'O disbelievers'" (Qul ya ayyuha al-kafirun); And in the third, "Say, 'He is Allah, [who is] One'" (Qul huwa Allahu ahad).