As far as Islamic Shari`ah is concerned, it is reported that Prophet Muhammad (peace and blessings be upon him) used to observe Witr Prayer even while traveling. Muslim scholars agreed on the importance of observing Witr, and some of them are of the opinion that it is obligatory and others are of the opinion that it is an important sunnah that every Muslim is highly recommended to observe it.
Sheikh Ahmad Kutty, a senior lecturer and Islamic scholar at the Islamic Institute of Toronto,Ontario, Canada, states: Witr is an important prayer, second only to the five daily Prayers. Its significance can be gauged from the fact that Prophet Muhammad (peace and blessings be upon him) was consistent in performing it, whether he was traveling or otherwise. There are certain reports attributed to him, although considered as weak by some, which also state that it is duty incumbent upon every Muslim. Imam Abu Hanifah considers Witr as obligatory; while others consider it as an important sunnah that no Muslim should neglect.
Coming to the manner of performing Witr, all of them agree that it should be performed after `Isha’ Prayer and before Fajr Prayer. As for the precise number of rak`ahs, there is latitude in it: One is free to pray three, five, seven, or any number of rak`ahs, as long as we end it in an odd number. Many consider it best to pray three rak`ahs, without any break; others say it is best to pray two rak`ahs, followed by a single rak`ah. According to some, it is perfectly fine to pray one rak`ah only. While praying three rak`as together, one group suggests that one should sit only in the last rak`ah, while others insist that one should read it as in Maghrib Prayer; for they say Witr is comparable to Maghrib, which is the Witr of the day.
The differences among scholars on this issue can be attributed to the fact that there is no hard and fast rule established by the Prophet (peace and blessings be upon him). He simply said, “Night Prayer should be done in two’s and two’s, but if one fears the arrival of Fajr, he should wrap it up by praying at least one rak`ah, thus ending it all in odd numbers.”
Another issue: Whether it is preferred to pray it right after `Isha’ or later, again, we find flexibility: When the Prophet’s beloved wife `A’ishah was asked about this, she said, “He did pray sometimes in the early part of the night, sometimes in the middle, and yet other times in the last (just before Fajr).” In other words, once again, there is no hard and fast rule. However, as she advised, if we are not sure of waking up for Tahajjud, then we should do Witr before sleep, otherwise, we are allowed to postpone it.