Praise be to Allaah.
It was proven that the Prophet (peace and blessings of
Allaah be upon him) prayed Witr in different ways. He prayed one rak’ah, and
three, and five, and seven, and nine. And he prayed three rak’ahs in two
different ways, either continuously with one tashahhud, or saying salaam
after two rak’ahs and praying one rak’ah and saying salaam after it. He did
not pray it like Maghrib, with two tashahhuds and one salaam. Rather he
forbade doing that, and said: “Do not pray Witr with three rak’ahs like
Maghrib.” Narrated by al-Haakim, 1/403; al-Bayhaqi, 3/31; al-Daaraqutni, p.
172. Al-Haafiz ibn Hajar said in Fath al-Baari (4/301): Its isnaad
fulfils the conditions of the two Shaykhs (al-Bukhaari and Muslim).
Shaykh Muhammad al-Saalih al-‘Uthaymeen said:
It is permissible to pray Witr with three rak’ahs, or with
five, or with seven, or with nine. If a person prays Witr with three, it may
be done in one of two ways, both of which are prescribed in sharee’ah:
1 – Praying the three rak'ahs continually with one tashahhud.
2 – Saying salaam after two rak’ahs, then praying one rak’ah
on its own.
Both of these are narrated in the Sunnah, so if a person does
it one way sometimes and the other way sometimes, that is good.
It is permissible to say
it with one salaam, but it should be with only one tashahhud and not two,
because if he does it with two tashahhuds, it will be like Maghrib prayer,
and the Prophet (peace and blessings of Allaah be upon him) forbade
making it like Maghrib prayer.
information please see question no.
3452, where there is a lengthy
and detailed discussion about qiyaam (night prayers) and Witr.