Fiqh-us-Sunnah Volume 2, Supererogatory Prayer, Fiqh 2.018.

According to al-Baihaqi and al-Hakim, the majority of the scholars maintain that it is correct to make qada’ for a missed witr prayer. Al-Hakim grades the following report by Abu Hurairah as sahih according to the criterion of al-Bukhari and Muslim.

Abu Hurairah reports that the Prophet said: “If the morning approaches, and you have yet to pray witr, you should pray the witr prayer.” Abu Dawud records from Abu Sa’id al-Khudri that the Prophet said: “If one of you sleeps [past the time of] the witr prayer or he forgets it, he should pray it when he remembers it.” Al-‘Iraqi says that the chain of this hadith is sahih.

Ahmad and at-Tabarani record with a hasan chain that the Prophet sallallahu alehi wasallam would perform the witr prayer in the morning [if, for some reason, he had missed it during the night].

Generally speaking, there is a difference of opinion over what time it may be made up. The Hanafi school holds it should be performed during those times in which it is not forbidden to observe prayers. The followers of Shaf’i say that it may be made up during any time of the night or day, while according to Malik and Ahmad a missed witr prayer is to be made up for after the dawn.