'Fasted' in the Bible

They mourned and wept and fasted until evening for Saul and his son Jonathan and for the people of the Lord and the house of Israel, because they had fallen by the sword.

David therefore inquired of God for the child; and David fasted and went and lay all night on the ground.

Then his servants said to him, “What is this thing that you have done? While the child was alive, you fasted and wept; but when the child died, you arose and ate food.”

He said, “While the child was still alive, I fasted and wept; for I said, ‘Who knows, the Lord may be gracious to me, that the child may live.’