The sole fast required by the law of Moses was that of the great Day of Atonement (q.v.), Lev. 23:26-32. It is called "the fast" (Acts 27:9).
The only other mention of a periodical fast in the Old Testament is in Zech. 7:1-7; 8:19, from which it appears that during their captivity the Jews observed four annual fasts.
1) The fast of the fourth month, kept on the seventeenth day of Tammuz, the anniversary of the capture of Jerusalem by the Chaldeans; to commemorate also the incident recorded Ex. 32:19. (Comp. Jer. 52:6, 7.)
2) The fast of the fifth month, kept on the ninth of Ab (comp. Num. 14:27), to commemorate the burning of the city and temple (Jer. 52:12, 13).
3) The fast of the seventh month, kept on the third of Tisri (comp. 2 Kings 25), the anniversary of the murder of Gedaliah (Jer. 41:1, 2).
4) The fast of the tenth month (comp. Jer. 52:4; Ezek. 33:21; 2 Kings 25:1), to commemorate the beginning of the siege of the holy city by Nebuchadnezzar.
There was in addition to these the fast appointed by Esther (4:16).
Public national fasts on account of sin or to supplicate divine favour were sometimes held.
1) 1 Sam. 7:6;
2) 2 Chr. 20:3;
3) Jer. 36:6-10;
4) Neh. 9:1.
There were also local fasts.
1) Judg. 20:26;
2) 2 Sam. 1:12;
3) 1 Sam. 31:13;
4) 1 Kings 21:9-12;
5) Ezra 8:21-23:
6) Jonah 3:5-9.
There are many instances of private occasional fasting (1 Sam. 1:7: 20:34; 2 Sam. 3:35; 12:16; 1 Kings 21:27; Ezra 10:6; Neh. 1:4; Dan. 10:2, 3). Moses fasted forty days (Ex. 24:18; 34:28), and so also did Elijah (1 Kings 19:8). Our Lord fasted forty days in the wilderness (Matt. 4:2).
In the lapse of time the practice of fasting was lamentably abused (Isa. 58:4; Jer. 14:12; Zech. 7:5). Our Lord rebuked the Pharisees for their hypocritical pretences in fasting (Matt. 6:16). He himself appointed no fast. The early Christians, however, observed the ordinary fasts according to the law of their fathers (Acts 13:3; 14:23; 2 Cor. 6:5).