Expositor's Bible Commentary Commentary Matthew 6:18

"that thou be not seen of men to fast, but of thy Father who is in secret: and thy Father, who seeth in secret, shall recompense thee." — Matthew 6:18 (ASV)

Yet Jesus, far from banning fasting, assumes his disciples will fast as well as give alms and pray (vv.3, 6). What he condemns is ostentation in fasting. Moreover he forbids any sign at all that a fast has been undertaken, because the human heart is so mixed in its motives that the desire to seek God will be diluted by the desire for human praise, thus vitiating the fast.

Washing and anointing with oil (v.17) were merely normal steps in hygiene.

The point of v.18 is not to draw attention to oneself, whether by somber mien or extravagant joy. Jesus desires reticence, not deception. And the Father, who sees in secret, will provide the reward (see comment on v.4).