But you, when you pray, enter into your inner room, and having shut your door, pray to your Father who is in secret; and your Father who sees in secret will reward you openly.
Shut the door
Everything about this instruction is about privacy: the room, the door, the secret. Jesus is suspicious of prayer that has an audience, even an audience of one's own self-regard. The inner room is a physical place, and it is also the interior itself: the place in you that no one sees.
Much of the noise in prayer is performance. We pray as if someone were listening in, composing sentences, managing an impression. Shutting the door means dropping all of that. There is no one to impress. The Father already sees. The prayer that follows can be wordless, halting, or nothing but a sitting still, and it is heard.
Practice
Find an actual door you can shut. Sit behind it for ten minutes today, and say nothing to God that you would not say if you were certain no one, including you, was judging it.
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