Wa `alaykum As-Salamu wa Rahmatullahi wa Barakatuh.
In the Name of Allah, Most Gracious, Most Merciful.
All praise and thanks are due to Allah, and peace and blessings be upon His Messenger.
Dear sister in Islam, thank you for the trust you place in us and your interesting question which is of general benefit. We implore Allah Almighty to help us serve His cause and render our work for His Sake.
Answering the question in point, Sheikh Ahmad Kutty, a senior lecturer and Islamic scholar at the Islamic Institute of Toronto, Ontario, Canada, states:
Witr can be performed in a number of ways such as the following:
1) Three rak`ahs with one salaam exactly as we perform the Maghrib Prayer, which has been the format followed by the Hanafi School. They have based this on a hadith reported by `A’ishah, the Mother of the Faithful, “The Prophet (peace and blessings be upon him) used to perform witr by praying three rak`ahs, saying salaam only upon finishing (the entire three rak`ahs).” (Muslim) As a further evidence they cite a statement of Abu al-`Aliyah, “The Prophet’s companions taught us to pray witr exactly as we perform Maghrib Prayer, since the former is witr of the night, and the latter is witr of the day.”
2) Three rak`ahs with just one salaam at the end but, unlike Maghrib, one skips the sitting after the two rak`ahs. This format of witr is considered acceptable according to both Shafi`i and Hanbali schools. They have relied on a report from the Prophet (peace and blessings be upon him) that he used to pray witr without sitting in between, but sitting only in the last rak`ah. (An-Nasa’i and al-Hakim)
3) Three rak`ahs are offered, but they are split into two parts; salaam is said after the first two rak`ahs, then following a slight pause, one stands up and prays another rak`ah followed by salaam. This is the format most preferred by the Maliki School, and they consider it undesirable to do it the other ways except when one is following an imam who adopts any of the other formats. They have based their opinion on a report from Ibn `Umar that the Prophet (peace and blessings be upon him) used to separate witr into two parts: two rak`ahs, followed by a single rak`ah, saying salaam after praying the two rak`ahs (as well as after the third). (Ahmad)
4) Praying more than three rak`ahs (i.e. five, seven, etc.), which has also been considered as permissible, according to Shafi`i and Hanbali schools. In their support they cite a number of traditions from the Prophet (peace and blessings be upon him) indicating the permissibility of doing the same.
As for the question, whether one can perform one rak`ah of witr all by itself, the scholarly opinion is divided on this issue.
According to both Shafi`i and Hanbali schools, one may perform one rak`ah of witr without incurring sin. It is not at all considered even as undesirable (makruh). This position is based on an authentic report from the Prophet (peace and blessings be upon him) which reads: “The (optional) night Prayer should be said in twos and twos; if you fear that dawn is approaching, finish it by praying witr, even if it be one rak`ah.” (Al-Bukhari and Muslim)
However, according to both the Hanafi and Maliki Schools—also endorsed by some scholars of the Hanbali School—praying one rak`ah of witr is considered as undesirable. However, they insist that one must do so if he were to pray behind an imam who has chosen to follow that format.
In light of the above discussion, it is reasonable to conclude that there is more than one valid way of performing witr. The imams or schools who have opted for one of the formats or another have not done so based on their whims or caprices but in strict conformity with the transmissions handed down to them from the Prophet or his companions.
If the Prophet (peace and blessings be upon him) had wanted the Ummah to rigidly follow a single format of witr, he would certainly have said so clearly and unambiguously, in which case the Ummah would have no choice but to stick to it.
As it was not the case, we find the above divergence of opinion. We may reflect on Imam Malik’s comment to one of the caliphs who wanted to enforce a single school of Fiqh on the Ummah: “Don’t attempt to do that, for the Companions have dispersed in the lands, each one of them carrying an aspect or aspects of the Sunnah.”
Almighty Allah knows best.