Question: how tahajjud prayer is performed?
Answer: "Salatul Layl (Night Prayer, i.e. Tahajjud) is offered as two rak'at followed by two rak'at and (so on) and if anyone is afraid of the approaching dawn (Fajr prayer) he should pray one rak'at and this will be a Witr for all the rak'at which he has prayed before."