'Acceptable' in the Bible

Thus saith Jehovah, In an acceptable time have I answered thee, and in a day of salvation have I helped thee; and I will preserve thee, and give thee for a covenant of the people, to raise up the land, to make them inherit the desolate heritages:

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?