NFL Muslim player penalised for praying.

Hamlet’s quote seems to indicate the NFL disagrees with you. It may have been improper conduct, but a penalty flag was the wrong way of dealing with it.

I saw a player just the other night in the end zone after a touchdown, doing the Namaste Gesture. This gesture is called Añjali Mudrā or Pranamasana. In Hinduism it means "I bow to the divine in you.

I haven’t heard anything about him being penalized, fined, suspended, banned, or imprisoned.

Again, at the moment the flag was thrown, the player was sliding on his knees in celebration, which is illegal. He then started praying, which sort of retroactively made it legal, but the flag was already thrown by then.

Of course nor. Arian Foster didn’t go to the ground, so there was no reason for him to have been flagged. What Foster did was akin to pointing up at heaven after a TD, which has never been an issue. What’s your point?