By Charles Spurgeon once remarked:
Public prayer is no evidence of piety. It is practised by an abundance of hypocrites. But private prayer is a thing for which the hypocrite has no heart.
E.M. Bounds made a similar statement, but in the context of learning how to pray:
Prayer is not learned in the classroom, but in the closet.
Prayer is one of the practises of godliness that we can do secretly. Unbelievers might hate it if you pray for them in public, but they can’t stop you from doing it secretly. Believers are even sometimes too embarrassed to ask for prayer and be prayed for by another, but you can do so in secret without them ever knowing.
This focus on excelling in secret prayer is the context for one of the times Jesus taught the famous “Our Father” prayer. In Matthew 6:1-18 we find the topic of secret prayer to be the bookends to the “Our Father”.
God sees in secret, so make it a place of prayer.