'Fasted' in the Bible

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

David therefore appealed to God for the child [to be healed]; and David fasted and went in 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 got up and ate food.”

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