Can a husband pray behind his wife individually while his wife prays individually in front in the room, meaning that they are both praying individually but the man is standing behind in the room?
All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah and that Muhammad is His slave and Messenger.
There is no problem when a man performs prayer individually behind his wife who is also performing prayer individually in the same room, and their prayers both are valid. There is no problem for a woman performing prayer to be physically in front of her husband. It has been narrated that the Prophet used to perform prayer while ʻAa'ishah was in front of him in the direction of the qiblah.
ʻAa’ishah said, "I used to stretch my legs in the qiblah of the Prophet while he was praying; whenever he prostrated, he touched me and I would withdraw my legs, and whenever he stood up, I would stretch my legs again." [Al-Bukhari]
ʻAa’ishah also said, "I saw the Prophet praying while I used to lie in (my) bed between him and the qiblah. Whenever I was in need of something, I disliked to sit and trouble the Prophet . So, I would slip away by the side of his feet." [Muslim]
Hence, this is proof that the woman's presence in front of the man does not affect the validity of his prayer.
Allaah knows best.
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