Is the prayer valid if one regularly recites the Qunut supplication in the Witr prayer after rising from rukoo’ (bowing)?

The Witr prayer is valid. Scholars have differed on the legitimacy of the Qunut in Witr: The Hanbalis, Hanafis, and some Shafi'is hold that it is a Sunnah, while the Malikis and Shafi'is hold that it is a Sunnah only in the latter half of Ramadan. The Malikis also have another opinion stating that it is not a Sunnah at all. Sheikh Al-Islam Ibn Taymiyyah mentioned that the Qunut in Witr is of the same nature as any permissible supplication in prayer, so whoever wishes may do it, and whoever wishes may leave it.