The Lord tells the prophet to cry aloud, like a trumpet, and declare to his people their transgression. They seek him daily and delight to know his ways, as if they were a nation that did righteousness. They ask why they fasted and he did not see, why they humbled themselves and he did not notice. The Lord answers that on the day of their fast they find their own pleasure and oppress all their workers. They fast only to quarrel and fight and to strike with a wicked fist. Such fasting will not make their voice heard on high.
Verses 6 and 7 describe the fast God wants: to loose the bonds of wickedness, to undo the straps of the yoke, to let the oppressed go free and to break every yoke; to share bread with the hungry, to bring the homeless poor into the house, to cover the naked and not to hide from your own flesh. Then your light will break forth like the dawn, your healing will spring up speedily, your righteousness will go before you and the glory of the Lord will be your rear guard. You will call and the Lord will answer: Here I am. If you give yourself to the hungry, your light will rise in the darkness and your gloom be as the noonday. The Lord will guide you continually, satisfy your desire and you will be like a watered garden. You will rebuild the ancient ruins and be called the repairer of the breach, the restorer of streets to dwell in.
The chapter ends with the Sabbath: if you turn back your foot from the Sabbath and from doing your pleasure on my holy day, if you call it a delight and honor it by not going your own ways, then you will take delight in the Lord, and I will make you ride on the heights of the earth and feed you with the heritage of Jacob your father. The mouth of the Lord has spoken.