NET
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.
Darby
18 so that thou mayest not appear fasting unto men, but to thy Father who is in secret; and thy Father who sees in secret shall render [it] to thee.
KJV
18 “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.”