Ibn 'Umar said "While the Prophet (ﷺ) was on the pulpit, a man asked him how to offer the night (prayers). He replied, Pray two Rak'at at a time and then two and then two and So on, and if you are afraid of the dawn (the approach of the time of the Fajr prayer) pray one Rak'a and that will be the Witr for all the Rak'at which you have offered." Ibn 'Umar said, Make an end of your (Tahajjud) night (prayer) with an odd Rak'a, for the Prophet (ﷺ) ordered it to be so." [1:461-O.B.]