1. In the OT.—‘To afflict the soul’ Is the term by which fasting is usually mentioned (cf. Lev_16:29-31; Lev_23:27; Lev_23:32, Num_29:7; Num_30:13; the two terms are combined in Psa_35:13, Isa_58:3; Isa_58:5). In the period preceding the Captivity we find no universal fast prescribed. The institution of the Day of Atonement—the only fast ordained in the Law—was traditionally ascribed to this period; but there is no certain reference to it before Sir_50:5 ff. Zechariah does not allude to it, and Eze_40:1-49; Eze_41:1-26; Eze_42:1-20; Eze_43:1-27; Eze_44:1-31; Eze_45:1-25; Eze_46:1-24; Eze_47:1-23; Eze_48:1-35 prescribes a more simple ceremonial for such an occasion, whence it may be inferred that the elaborate ritual of Lev_16:1-34 was not yet customary. Neh_7:73 to Neh_9:38 records a general fast on the 24th day of the 7th month, and therefore the 10th day of that month—the proper date for the Day of Atonement—was probably not yet set apart for this purpose. Moreover, the characteristic ideas of the fast—its public confession, its emphasis on sin and atonement—are late, and can be compared with post-exilic analogies (Ezr_9:1-15, Neh_1:4-11; Neh_9:3). See Atonement [Day of]. Previously to the Captivity fasting was observed by individuals or the whole people on special occasions (cf. 2Sa_12:16, 1Ki_21:27, Jdg_20:26, 1Sa_7:6, 2Ch_20:3).
After the Captivity this type of fasts of course continued (cf. Ezr_8:21-23, Neh_1:4; Neh_9:1). But in Zec_7:3-5; Zec_8:19 we hear of four general fasts which were observed with comparative regularity. On 17th Tammuz (July) a fast was ordained to commemorate the capture of Jerusalem by Nebuchadnezzar (Jer_39:2; Jer_52:6). This was celebrated on the 17th day of the 4th month, and not on the 9th, because, according to the Talmudic tradition, the 17th was the day on which Moses broke the tables of the Law, on which the daily offering ceased owing to the famine caused by the Chaldæan siege, and on which Antiochus Epiphanes burnt the Law and introduced, an idol into the Holy Place. On the 9th day of the 5th month (Ab) was celebrated a fast in memory of the burning of the Temple and city (2Ki_25:8, Jer_52:12). The 9th, and not the 7th or 10th, was the prescribed day, because tradition placed on the 9th the announcement that the Israelites were not to enter Canaan, and the destruction of the Second Temple. On the 3rd of Tishri (October) the murder of Gedaliah was commemorated by a fast (Jer_41:1), and on the 10th of Tebeth (January) another fast recalled the siege of Jerusalem by the Chaldæans (2Ki_25:1, Jer_52:4). Besides these, we hear of a Fast of Esther being observed; on this see Purim.
Fasting probably meant complete abstinence, though the Talmud allowed lentils to be eaten during the period of mourning. No work was done during a fast (Lev_16:29; Lev_16:31; Lev_23:32, Num_29:7), and sackcloth and ashes were sometimes used (Dan_9:3, Jon_3:6-7). The usual reasons for a fast were either mourning (1Sa_31:13) or a wish to deprecate the Divine wrath (2Sa_12:16-17).
2. In the NT.—We hear that frequent additional fasts were imposed by tradition, and that strict observers kept two weekly fasts (Luk_18:12)—on Thursday and Monday—commemorating, as it seems, the days on which Moses ascended and came down from the Mount. After the destruction of Jerusalem by Titus, a huge system of fasts was instituted, and the present Jewish calendar prescribes 22, besides the Day of Atonement, the Fast of Esther, and the four fasts of Zec_8:19.
3. Christianity and fasting.—Jesus refused to lay down any specific injunctions to fast. To prescribe forms was not His purpose; all outward observance was to be dictated by an inward principle. He Himself probably kept the usual fasts, and individual ones, as during the Temptation. But He laid emphasis in His teaching on the inutility of fasting except as a part of personal godliness, and gave plain warnings of its possible abuse by hypocrisy (Mat_6:16-18; Mat_9:14-17, Mar_2:18-22, Luk_5:33-39). The early Church used to fast before solemn appointments (Act_13:2; Act_14:23); and St. Paul alludes to his fastings, whether voluntary or compulsory, in 2Co_6:5; 2Co_11:27. In time a greater stress was put on the value of fasting, as is shown by the probable insertion of an allusion to it in Mat_17:21, Mar_9:29, Act_10:30, 1Co_7:5.