You don’t have to pray on your knees. I don’t think it’s disrespectful to pray in bed, either. Pray how you’re comfortable. The best kind of prayer, and time for prayer, is the time when you’ll do it.
You can bet that paratroopers in war have been praying on their way down. Those escaping from hostage takers prayed as they ran. Exceptional cases of course, but prayer is most of all from the heart.
If you are able to kneel, then by all means go right ahead. But there is no demand for a cerain bodily position - rather a dis-position of the heart.
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