Isaiah contrasted God's conception of fasting with that of His people.
58:6 The type of fasting that pleases God is giving up wickedness, oppression, enslavement, and binding of other people, not just food. Isaiah did not mean, of course, that God had no concern about His people going without food (cf. Lev. 16:31). The prophet was going to the opposite extreme to make a point (cf. 1:10-20; Amos 5:25-27; Mic. 6:6-8; Luke 14:26).
"If they want to deprive themselves, let them do it for the sake of the oppressed, the needy, and the helpless, not for the sake of their own religiosity. God's nature is to give himself away to those who can never repay him. There is no clearer evidence of the presence of God in a person's life than a replication of that same behavior."661
God wants people to be free. That is why He sent the Servant, and that is why He liberated the Israelites from Egypt and Babylon. He wants His people to set others free too.
"To loose the chains of injustice/'fetters of wickedness' points to the need to labour for the abolition of every way in which wrong social structures, or wrongdoers in society, destroy or diminish the due liberty of others. To untie the cords of the yokerefers to the need to eliminate every way in which people are treated like animals."662
58:7 Likewise helping the poor is more important than helping oneself. Feeding the hungry, housing the homeless, and clothing the naked are more important to God than living well oneself. What is the point of fasting if we do not give what we would eat to others? Self-denial should be for others, not for oneself (cf. Matt. 25:35; Luke 3:11; 10:31-32; Heb. 13:2).
"No religious observance has value for Jehovah that is not supported by a godly, law-abiding life, and compassion towards those in need."663
58:8 This type of reality would produce many good consequences. Light would dispel the Israelites' darkness. They would recover their spiritual wholeness quickly. Their righteousness (God Himself) and their right conduct (cf. 56:1) would precede them, and God's glory would protect them.664
58:9 The Lord would hear their prayers, and they would enjoy His presence (cf. vv. 1-3). Making self the focus of life, in contrast, results in darkness (cf. 5:20; 8:20; 47:5; 60:2), disease (cf. 1:5), defeat (cf. 1:7), and separation (cf. 1:4). For these blessings to come, God's people needed to stop oppressing others, and to stop mocking and showing contempt for others with wicked speech (cf. 57:4; 66:5).665It is possible that "the pointing of the finger"may refer to being critical of others who are not as socially sensitive as oneself.666
58:10 Positively, God's people needed to alleviating hunger in others (rather than creating it in themselves by fasting), and to pour out their lives for others. Then they would have light even in gloom because God would be with them, and God is light (cf. 1 John 1:5).
58:11 God would also guide and sustain His people in their desert experiences. Strong bones contrast with bones that tremble or waste away because of fear, sorrow, or guilt. Physical health is often a byproduct of spiritual health (cf. James 5:15-16). Truly repentant people will also be a pleasant source of delight, encouragement, and nourishment to others (cf. 1:30). They will refresh others as well as themselves because God, the source of life within them (cf. John 4:14; 7:37-39), will manifest Himself through them.
58:12 True worshippers would also rebuild what their sin had previously torn down. This refers not only to the return and rebuilding of Jerusalem and Judah following the exile but the Promised Land in the Millennium. It also refers to the restoration of other types of ruins caused by sin.
The remaining two verses continue the explanation of true worship begun in verse 6, but they also conclude this chapter by returning to consider proper response to a specific aspect of the Mosaic legislation, namely, Sabbath observance.
58:13 If the Israelites practiced the Mosaic legislation with the right attitude and applied it properly to their lives, God would be happy. Isaiah was not saying the Mosaic legislation was wrong, only that the legislation as his audience was practicing it was not pleasing to God. They were obeying to further their own selfish purposes. They should have obeyed to further God's purposes out of love for Him (cf. Matt. 6:10). For the Israelites, Sabbath observance was best suited to teach this lesson. The Sabbath day provided an opportunity for them to reorient themselves to spiritual reality once a week. It was not a fast but a feast day.
"The Lord is more interested in enjoyment of his blessings through obedience than in self-imposed deprivations."667
"Turn your foot"means watch your step (cf. Eccles. 5:1).
58:14 Turning from a false approach to the Sabbath, and all the Law, would mean turning to the Lord with the proper attitude of delight. Then the Israelites would experience the exaltation of being His partners and would enjoy the inheritance promised to their all-too-human ancestor Jacob (cf. v. 1). If they would give themselves to God and others rather than pursuing selfish goals, they would experience personal and national fulfillment and receive His rewards. This was a promise from the mouth of Yahweh.
(NT only) to listen to the NET Bible 
