Duwaid bin Nafi’ said: “Ibn Shihab informed me, saying: ‘Ata’ bin Yazid narrated to me from Abu Ayyôb: That the Prophet صلی اللہ علیہ وآلہ وسلم said: ‘Witr is a duty, and whoever wants to pray Witr with seven (Rak’àhs), let him do so; whoever wants to pray Witr with five, let him do so; whoever wants to pray Witr with three, let him do so; and whoever wants to pray Witr with one, let him do so.” (Sahih)