'Fast' in the Bible

Blessed is the one who does this, and the person that holds it fast, who observes the Sabbath without profaning it, and restrains his hands from practicing any evil.

For this is what the LORD says: "To the eunuchs who observe my Sabbaths, who choose the things that please me, and who hold fast my covenant

"Also, the foreigners who join themselves to the LORD, to minister to him, to love the name of the LORD, to be his servants, and to bless the LORD'S name, observing the Sabbath without profaning it, and who hold fast my covenant

"Why have we fasted,' they ask, "but you do not see? "Why have we humbled ourselves,' they ask, "but you take no notice?'" "Look! On your fast day you serve your own interest and oppress all your workers.

"Look! You fast only for quarreling, and for fighting, and for hitting with wicked fists. You cannot fast as you do today and have your voice heard on high.

"Is this the kind of fast that I have chosen, merely a day for a person to humble himself? Is it merely for bowing down one's head like a bulrush, for lying on sackcloth and ashes? Is this what you call a fast, an acceptable day to the LORD?

Isn't this the fast that I have been choosing: to loose the bonds of injustice, and to untie the cords of the yoke, and to let the oppressed go free, and to break every yoke?