KJV - But thou, when thou prayest, enter into thy closet, and when thou hast shut thy door, pray to thy Father which is in secret; and thy Father which seeth in secret shall reward thee openly.
NLT - But when you pray, go away by yourself, shut the door behind you, and pray to your Father in private. Then your Father, who sees everything, will reward you.
I didn't understand this verse for a long time, because I had heard one too many sermons with a legalistic overtone about it. I don't believe Jesus is condemning all public prayer. What He is trying to tell us is to go behind the closed door, so we are not distracted by the noisy world, and we are away from prying eyes.
In that quiet moment, we can open our hearts and bare our souls to Father God. Just as we've been learning from the previous days' verses; we can cry out to Him and He will hear us.
The "closet" is the closed place, where we are shut in alone with God, where the human spirit waits upon an unseen Presence, learns to recognize Him who is a Spirit, and cultivates His acquaintance, fellowship, and friendship.
The other facet of this verse is the 'why' behind it. Jesus specifically pointed to the Pharisees, who would grand-stand their prayers, waiting to be seen by all the passersby. These are ineffective prayers, since they are being given for the praise of men, not the glory of God.
Pride. Gets us every time, doesn't it? Satan loves to use it against us to keep us near to God. He may be able to do a lot of things; however, I scarcely believe he can fake a pure heart in commune with Father God. Go to your quiet place today. Shut the door to the world, and just open up and talk to Him. He is waiting for you.
What does this verse speak to you?