16"When you fast, do not look somber as the hypocrites do, for they disfigure their faces to show men they are fasting. I tell you the truth, they have received their reward in full. 17But when you fast, put oil on your head and wash your face, 18so that it will not be obvious to men that you are fasting, but only to your Father, who is unseen; and your Father, who sees what is done in secret, will reward you."
In these verses, Jesus continues His teaching concerning ostentation in performing spiritual acts. Recall that He has warned us against ostentation in giving to the poor (see Matt. 6:2-4), and in praying (see Matt. 6:5-8). Here, He warns against ostentation during fasting: "When you fast, do not look somber as the hypocrites do, for they disfigure their faces to show men they are fasting. I tell you the truth, they have received their reward in full" (vs. 16).
Fasting was a not uncommon practice of the Pharisees, as well as of the early church. In the Old Testament, fasting was commanded for one occasion: the Day of Atonement (see Lev. 16:29-31; 23:27-32; Num. 29:7). Beyond this, fasting was voluntary. There are many examples of fasting in the Old Testament. Most of the examples are fasts carried out by groups of people in prayer for God's help during times of distress, or in prayer seeking the guidance of God when an important decision needs to be made (see Judges 20:26; Neh. 9:1-2; Jonah 3:5; II Sam. 1:12; II Chron. 20:3; Ezra 8:21-23; Esth. 4:16). Fasting continued on in the early New Testament church (e.g., Acts 13:1-3; Acts 14:23), and of course, is still practiced today.
The purpose of fasting is to bring the body into subjection to the Spirit. Fasting is accompanied by prayers, for which the discernment and/or power of the Spirit is especially needful. "Prayer may be said to be that by which we attach ourselves to God, and fasting that by which we detach ourselves from the world." Though fasting starves the body, it simultaneously fattens the soul. Jesus in this passage assumes his disciples (including us) will fast from time to time. He says: "When you fast..." We all go through times of distress, or times of especial perplexion concerning God's direction. These are the times to fast.
Jesus, later, also seems to indicate that there are times when fasting is inappropriate. Times of rejoicing are not times to fast (see Matt. 9:14-17). "The Saviour clearly teaches that fasting is right only when one's condition makes it natural. In a time of joy, fasting would be unnatural, and could not express a genuine feeling. But persons who are in great distress are naturally inclined to abstain from eating."
Specific times of fasting are not commanded for Christians. "It seems to be left to everyone's discretion, whether he will fast or not. In this absence of direct command, we may see great wisdom. Many a poor man never has enough to eat, and it would be an insult to tell him to fast; many a sickly person can hardly be kept well with the closest attention to diet, and could not fast without bringing on illness. It is a matter in which every one must be persuaded in his own mind, and not rashly condemn others who do not agree with him."
As stated, the purpose of Jesus' teaching in this passage is to warn us against ostentation when we do fast: "[D]o not look somber as the hypocrites do, for they disfigure their faces to show men they are fasting" (vs. 16). It is implied that these hypocrites are going out of their way to look miserable in order impress men, attempting to let others know how "holy" they are by their fasting. To do such a thing, of course, is ridiculous. "To look miserable in order to be thought holy is a wretched piece of hypocrisy." And beyond hypocrisy, to look miserable when one is not really suffering is a great insult to God, who has blessed us so much. Jesus suggests that those who fast with such hypocrisy will not have their prayers heard by God: "I tell you the truth, they have received their reward in full" (vs. 16). Their reward is any praise from men that they might possibly receive from their hypocrisy.
Jesus instructs us how properly to fast: "But when you fast, put oil on your head and wash your face, so that it will not be obvious to men that you are fasting, but only to your Father, who is unseen; and your Father, who sees what is done in secret, will reward you" (vs. 17-18). To "put oil on [one's] head and wash [one's] face" was the normal way to prepare oneself for going out in those times. And so, Jesus here is saying that, when you fast, you should go through your normal daily regimen and dress normally, so as not to draw especial attention to your fast. After all, you are not fasting to get the attention of man, but to get the attention of God, to bring your petitions to Him with the power of the Spirit, as you ignore the desires of your flesh. And be sure: God "sees what is done in secret", and Jesus assures us that He will "reward" us.
We praise You Father, that You hear our prayers, listen attentively, and in all Your goodness, answer our prayers. Give us, through the work of Your Spirit, a pure heart. May we not seek the praise of men for ourselves, but rather, may we be faithful witnesses of Your greatness, so that those who see us, may praise and glorify You. In the name of Jesus, our Teacher and Savior, we ask these things, Amen.