Matthew 6:6

6:6 But whenever you pray, go into your room, ¹  close the door, and pray to your Father in secret. And your Father, who sees in secret, will reward you. ² 

Matthew 6:18

6:18 so that it will not be obvious to others when you are fasting, but only to your Father who is in secret. And your Father, who sees in secret, will reward you.

¹ sn The term translated room refers to the inner room of a house, normally without any windows opening outside, the most private location possible (BDAG 988 s.v. ταμεῖον 2).

² tc See the tc note on “will reward you” in 6:4: The problem is the same and the ms support differs only slightly.