Is it valid for me to pray three rak’ahs for Witr—two as shaf‘ and one as witr—while a doctor of Sharia issued a fatwa that whoever prays only one rak’ah after ‘Isha’ will have the reward of having prayed the whole night (qiyam al-layl)?

The relied-upon opinion is that the minimum for Witr is one rak'ah, and the minimum for its perfection is three rak'ahs; there is no contradiction between the two matters. Jurists have differed on this: The Shafi'is and Hanbalis permit Witr with one rak'ah without dislike, basing their argument on the hadith (definition): "The night prayer is two by two, and when you fear the dawn, pray one rak'ah as Witr." As for the Hanafis, they do not permit Witr with one rak'ah due to the Prophet's prohibition of the batra' (the amputated prayer). The hadith prohibiting the batra' is considered weak by some scholars.