It was narrated from Ubayy bin Ka’b that the Messenger of Allah صلی اللہ علیہ وآلہ وسلم used to pray Witr with three Rak’ahs. In the first he would recite: “Glorify the Name of your Lord, the Most High” in the second: “Say: O you disbelievers!”; and in the third: “Say: He is Allah, (the) One”. And he would say the Qunat before bowing, and when he finished he would say: Sub Malikil-Quddus (Glory be to the Sovereign, the Most Holy) three times, elongating the words the last time. (Sahih)