'Fast' in the Bible

Blessed is the man that doeth this, and the son of man that holdeth it fast; that keepeth the sabbath from profaning it, and keepeth his hand from doing any evil.

For thus saith Jehovah of the eunuchs that keep my sabbaths, and choose the things that please me, and hold fast my covenant:

Also the foreigners that join themselves to Jehovah, to minister unto him, and to love the name of Jehovah, to be his servants, every one that keepeth the sabbath from profaning it, and holdeth fast my covenant;

Wherefore have we fasted,'say they , and thou seest not? wherefore have we afflicted our soul, and thou takest no knowledge? Behold, in the day of your fast ye find your own pleasure, and exact all your labors.

Behold, ye fast for strife and contention, and to smite with the fist of wickedness: ye fast not this day so as to make your voice to be heard on high.

Is such the fast that I have chosen? the day for a man to afflict his soul? Is it to bow down his head as a rush, and to spread sackcloth and ashes under him? wilt thou call this a fast, and an acceptable day to Jehovah?

Is not this the fast that I have chosen: to loose the bonds of wickedness, to undo the bands of the yoke, and to let the oppressed go free, and that ye break every yoke?