Matthew 6:18 in the King James Version
That thou appear not unto men to fast, but unto thy Father which is in secret: and thy Father, which seeth in secret, shall reward thee openly.
Context
17 But you, when you fast, anoint your head and wash your face,
18 so that you are not seen by men to be fasting, but by your Father who is in secret; and your Father, who sees in secret, will reward you.
19 “Don’t lay up treasures for yourselves on the earth, where moth and rust consume, and where thieves break through and steal;