The prayer is valid.

if a person deliberately makes a slight error in their posture during salah, such as bending the knees a bit during ruku, would this invalidate their prayer?

Prayer | November 5, 2015 3:22 am
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1) i live in france and i have a restaurant alhamdoulilah . But i can t pray dhohr , maghreb and isha in the masjid because i have to be in the restaurant so i pray in the restaurant is it permissible ? 2) can i stay in france? I was born here, i m 25. I am single and live with my family. I can practice my religion without restriction alhamdulilah.
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One of my uncles keeps chair behind him so he will able to sit and do bow and prostration. As he is able to stand, he stands and prays (where he needs to stand) but he always quite ahead (more then feet) from the row of congregation due to chair. Does it invalid his prayer or make any effects on congregation?