Can the Qiyaam al-Layl (Night prayer) be reading Quran only or does it have to be praying?
All perfect praise be to Allah, The Lord of the Worlds. I testify that there is none worthy of worship except Allah, and that Muhammad is His slave and Messenger.
The night prayer (Qiyaam) can only be by praying.
Nonetheless, it is known that there is a reward in the recitation of the Quran and in the mention of Allah.
Allah knows best.
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