Matthew 6:16

Fasting in Israel involved going without food to engage in a spiritual exercise, usually prayer, with greater concentration. Fasting fostered and indicated self-humiliation before God, and confession often accompanied it (Nehemiah 9:1-2; Psalms 35:13; Isaiah 58:3; Isaiah 58:5; Daniel 9:2-20; Daniel 10:2-3; Jonah 3:5; Acts 9:9). People who felt anguish, danger, or desperation gave up eating temporarily to present some special petition to the Lord in prayer (Exodus 24:18; Judges 20:26; 2 Samuel 1:12; 2 Chronicles 20:3; Ezra 8:21-23; Esther 4:16; Matthew 4:1-2; Acts 13:1-3; Acts 14:23). Some pious believers fasted regularly (Luke 2:37). The Pharisees fasted twice a week (Luke 18:12). God only commanded the Israelites to fast on one day of the year, the Day of Atonement (Leviticus 16:29-31; Leviticus 23:27-32; Numbers 29:7). However during the Exile the Israelites instituted additional regular fasts (Zechariah 7:3-5; Zechariah 8:19). Fasting occurred in the early church and seems to have been a normal part of Christian self-discipline (1 Corinthians 9:24-27; Philippians 3:19; 1 Peter 4:3). Hypocritical fasting occurred in Israel long before Jesus’ day (Isaiah 58:1-7; Jeremiah 14:12; Zechariah 7:5-6), but the Pharisees were notorious for it.

"Fasting emphasized the denial of the flesh, but the Pharisees were glorifying their flesh by drawing attention to themselves." [Note: Barbieri, p. 32.]

Jesus’ point in this verse was that His disciples should avoid drawing attention to themselves when they fasted. He did not question the genuine contrition of some who fasted, but He pointed out that the hypocrites wanted the admiration of other people even more than they wanted God’s attention. Since that is what they really wanted, that is all they would get.