Matthew 6:6

Σὺ δὲ ὅταν προσεύχῃ, εἴσελθε εἰς τὸ ταμιεῖόν σου· καὶ κλείσας τὴν θύραν σου, πρόσευξαι τῷ Πατρί σου τῷ ἐν τῷ κρυπτῷ· καὶ ὁ Πατήρ σου ὁ βλέπων ἐν τῷ κρυπτῷ, ἀποδώσει σοι ἐν τῷ φανερῷ.

But you, when you pray, enter into your room and shut your door, pray to your Father who is in secret; and your Father who sees in secret will reward you in the open.