Is it permissible to offer Witr

Q 6: I always wake up in the last third of the night to perform Tahajjud (optional late night Prayer), but once did so without performing Witr (Prayer with an odd number of units). Was my Salah (Prayer) valid? Is it obligatory for me to perform Witr? Must I offer it before Tahajjud? Which is better for me, to perform Witr or Tahajjud? How many Rak`ahs should I perform in Tahajjud? I hope that you will give me a detailed answer.

A: If anyone fears that they will not be able to wake up at night, they should not delay the Witr until the last part of the night; it is permissible for them to offer Witr at the beginning of the night. If they then wake up and perform Salah (Prayer) in the night, they will not have to repeat the Witr. However, if they expect to wake up to offer Tahajjud in the last part of the night, they may delay Witr to perform it with Tahajjud. It should be noted that Tahajjud should be offered in pairs of Rak`ahs (units of Prayer). (Part No. 7; Page No. 181) If while offering Tahajjud, it is feared that the time for the Fajr (Dawn) Prayer is very near, one Rak`ah should be performed. The Prophet (peace be upon him) usually performed eleven Rak`ahs in Qiyam-ul-Layl (optional Prayer at night), but there is no harm in doing more or less than this.May Allah grant us success. May peace and blessings be upon our Prophet Muhammad, his family, and Companions.