Is it permissible to pray one Rak'ah as Witr before sleeping without the Shaf' prayer, and will whoever does so be rewarded as a martyr, as stated in the Hadith: "Whoever prays Duha, fasts three days of the month, and never abandons Witr whether traveling or resident, will have the reward of a martyr written for him"?

The aforementioned Hadith (definition) is weak, but authentic proofs have indicated the permissibility of all that was mentioned in it. Thus, it is recommended to maintain the Duha prayer, fasting three days of every month, and Witr is among the most emphasized Sunnahs. Limiting Witr to one rak'ah is permissible and fulfills the basic Sunnah (definition), and it is not disliked. However, it is better and more complete to perform Witr with more than one rak'ah, and the minimum for completeness is three rak'ahs.