Answer
(Fatwa: 644/644=M/1429)
There is no contradiction between Dr. Abdul Hayi (RA) and our previous Fatwa. The time of Namaz-e-Tahajjud starts after the Fardh of Isha prayer and remains til the time of Fajar prayer starts. The reason of your misunderstanding in this matter is that you have considered Witr prayer part of Isha prayer, while Witr prayer itself is a Wajib prayer, and its time is also after Isha prayer. Now, if anyone sleeps or does not sleep after performing the Fardh and Sunnah of Isha prayer and performs Tahajjud prayer before Witr prayer then his Tahajjud prayer shall be valid. The practice of the Holy Prophet (PBUH) used to perform Witr prayer after Tahajjud in last night. It is obvious to note that in previous Fatwa the Afzal (best) time of Tahajjud prayer was mentioned, you are kindly advised to read it again. However, as far as the number of Rakats of Tahajjud is concerned, the minimum rakah is two and maximum is eight rakah.
و فی الشامی: فينبغي القول بأن أقل التهجد ركعتان و أوسطه أربع و أكثره ثمان.
Allah (Subhana Wa Ta’ala) knows Best
Darul Ifta,
Darul Uloom Deoband