Although, from the standpoint of the sunnah, there is no specific evidence for it, as long as some imams have held this view and it has a basis in juristic reasoning—even if it is mistaken—then, so long as it is not prohibited, why should we exclude, disparage, declare mistaken, or brand as an innovator someone who does something that we do not hold to be correct? And since the matter is not yours to decide, but your imam does it, there is no objection to doing it.
Consider the imams who understood the value of unity. Imam Ahmad, may Allah have mercy on him, held that the qunut in the Fajr prayer was an innovation, yet he would say: “If you are behind an imam who performs qunut, then follow him in his qunut and say amin to his supplication.” All of this is for the sake of unity, harmony of hearts, and preventing us from disliking one another.
The one who performs tahajjud should pray witr after it; if he follows his imam, he should make it even by adding a rak'ah ………
His statement, “The one who performs tahajjud should pray witr after it”: “After it” means after his tahajjud—that is, if a person wishes to perform tahajjud after Tarawih at the end of the night,