Fast; Fasting

Boyd’s Bible Dictionary:

(keep). One legal fast, the Atonement, kept by Jews (Lev. 16:29-3429And this shall be a statute for ever unto you: that in the seventh month, on the tenth day of the month, ye shall afflict your souls, and do no work at all, whether it be one of your own country, or a stranger that sojourneth among you: 30For on that day shall the priest make an atonement for you, to cleanse you, that ye may be clean from all your sins before the Lord. 31It shall be a sabbath of rest unto you, and ye shall afflict your souls, by a statute for ever. 32And the priest, whom he shall anoint, and whom he shall consecrate to minister in the priest's office in his father's stead, shall make the atonement, and shall put on the linen clothes, even the holy garments: 33And he shall make an atonement for the holy sanctuary, and he shall make an atonement for the tabernacle of the congregation, and for the altar, and he shall make an atonement for the priests, and for all the people of the congregation. 34And this shall be an everlasting statute unto you, to make an atonement for the children of Israel for all their sins once a year. And he did as the Lord commanded Moses. (Leviticus 16:29‑34); Deut. 9:99When I was gone up into the mount to receive the tables of stone, even the tables of the covenant which the Lord made with you, then I abode in the mount forty days and forty nights, I neither did eat bread nor drink water: (Deuteronomy 9:9); Jonah 3:55So the people of Nineveh believed God, and proclaimed a fast, and put on sackcloth, from the greatest of them even to the least of them. (Jonah 3:5); Zech. 7:1-71And it came to pass in the fourth year of king Darius, that the word of the Lord came unto Zechariah in the fourth day of the ninth month, even in Chisleu; 2When they had sent unto the house of God Sherezer and Regem-melech, and their men, to pray before the Lord, 3And to speak unto the priests which were in the house of the Lord of hosts, and to the prophets, saying, Should I weep in the fifth month, separating myself, as I have done these so many years? 4Then came the word of the Lord of hosts unto me, saying, 5Speak unto all the people of the land, and to the priests, saying, When ye fasted and mourned in the fifth and seventh month, even those seventy years, did ye at all fast unto me, even to me? 6And when ye did eat, and when ye did drink, did not ye eat for yourselves, and drink for yourselves? 7Should ye not hear the words which the Lord hath cried by the former prophets, when Jerusalem was inhabited and in prosperity, and the cities thereof round about her, when men inhabited the south and the plain? (Zechariah 7:1‑7)). Special fasts observed (1 Sam. 7:66And they gathered together to Mizpeh, and drew water, and poured it out before the Lord, and fasted on that day, and said there, We have sinned against the Lord. And Samuel judged the children of Israel in Mizpeh. (1 Samuel 7:6); Jer. 36:6-106Therefore go thou, and read in the roll, which thou hast written from my mouth, the words of the Lord in the ears of the people in the Lord's house upon the fasting day: and also thou shalt read them in the ears of all Judah that come out of their cities. 7It may be they will present their supplication before the Lord, and will return every one from his evil way: for great is the anger and the fury that the Lord hath pronounced against this people. 8And Baruch the son of Neriah did according to all that Jeremiah the prophet commanded him, reading in the book the words of the Lord in the Lord's house. 9And it came to pass in the fifth year of Jehoiakim the son of Josiah king of Judah, in the ninth month, that they proclaimed a fast before the Lord to all the people in Jerusalem, and to all the people that came from the cities of Judah unto Jerusalem. 10Then read Baruch in the book the words of Jeremiah in the house of the Lord, in the chamber of Gemariah the son of Shaphan the scribe, in the higher court, at the entry of the new gate of the Lord's house, in the ears of all the people. (Jeremiah 36:6‑10); Esther 4:1616Go, gather together all the Jews that are present in Shushan, and fast ye for me, and neither eat nor drink three days, night or day: I also and my maidens will fast likewise; and so will I go in unto the king, which is not according to the law: and if I perish, I perish. (Esther 4:16); Matt. 9:1414Then came to him the disciples of John, saying, Why do we and the Pharisees fast oft, but thy disciples fast not? (Matthew 9:14); Mark 2:1818And the disciples of John and of the Pharisees used to fast: and they come and say unto him, Why do the disciples of John and of the Pharisees fast, but thy disciples fast not? (Mark 2:18); Luke 5:3333And they said unto him, Why do the disciples of John fast often, and make prayers, and likewise the disciples of the Pharisees; but thine eat and drink? (Luke 5:33); Acts 10:30; 13:330And Cornelius said, Four days ago I was fasting until this hour; and at the ninth hour I prayed in my house, and, behold, a man stood before me in bright clothing, (Acts 10:30)
3And when they had fasted and prayed, and laid their hands on them, they sent them away. (Acts 13:3)
).

Concise Bible Dictionary:

The first fasting we read of is when Moses went up into the mount to receive the tables of the covenant, and was there apart from nature with the Lord for forty days and nights (Deut. 10:1010And I stayed in the mount, according to the first time, forty days and forty nights; and the Lord hearkened unto me at that time also, and the Lord would not destroy thee. (Deuteronomy 10:10)). The first national fasting was when Israel was smitten before Benjamin: they "came unto the house of God, and wept, and sat there before the Lord, and fasted that day until even, and offered burnt offerings and peace offerings before the Lord" (Judg. 20:2626Then all the children of Israel, and all the people, went up, and came unto the house of God, and wept, and sat there before the Lord, and fasted that day until even, and offered burnt offerings and peace offerings before the Lord. (Judges 20:26)). Here, as in other places, it is connected with humbling; but in the case of Elijah, as with Moses, it signifies being apart from the ordinary life of flesh, to be with the Lord (1 Kings 19:88And he arose, and did eat and drink, and went in the strength of that meat forty days and forty nights unto Horeb the mount of God. (1 Kings 19:8)). Jehoshaphat, when the children of Moab and of Ammon came against him, proclaimed a fast throughout all Judah, and asked help of the Lord (2 Chron. 20:33And Jehoshaphat feared, and set himself to seek the Lord, and proclaimed a fast throughout all Judah. (2 Chronicles 20:3)). When Nineveh was threatened with destruction the king humbled himself, proclaimed a fast, and put on sackcloth: every one was to cry mightily to God, and put away his evil (Jonah 3:55So the people of Nineveh believed God, and proclaimed a fast, and put on sackcloth, from the greatest of them even to the least of them. (Jonah 3:5)). The only fast enjoined by the law was the one connected with the Day of Atonement. The word “fasting” does not occur there, but it is held to be included in the injunction “afflict your souls.” This seems to be confirmed by “the fast” mentioned in Acts 27:99Now when much time was spent, and when sailing was now dangerous, because the fast was now already past, Paul admonished them, (Acts 27:9), for the tenth of Tisri would answer to the time of the equinoctial gales, when it was dangerous to sail in the Mediterranean.
In the N.T. we find in John the Baptist the spirit of fasting, a Nazarite spirit of separation (Matt. 3:44And the same John had his raiment of camel's hair, and a leathern girdle about his loins; and his meat was locusts and wild honey. (Matthew 3:4)). He also taught his disciples to fast. The Lord said of His disciples that when He was taken away, then they would fast; and while He was here He spoke of a certain power over unclean spirits that could only be exercised with prayer and fasting (Matt. 17:2121Howbeit this kind goeth not out but by prayer and fasting. (Matthew 17:21)). He Himself when led up of the Spirit into the wilderness to be tempted of the devil, fasted forty days and forty nights. It is a contrast to Moses and Elijah, they were apart from man's natural condition to be with God; and He who as man was ever with God was so apart to be in conflict with the devil.
Paul and Barnabas were sent on their first missionary journey after prayer and fasting (Acts 13:2-32As they ministered to the Lord, and fasted, the Holy Ghost said, Separate me Barnabas and Saul for the work whereunto I have called them. 3And when they had fasted and prayed, and laid their hands on them, they sent them away. (Acts 13:2‑3)). It is to be feared that because many have made fasting compulsory, and attached a superstitious merit to it, other Christians have altogether neglected the uniting of fasting with prayer. An habitual self-denial is doubtless the spirit of fasting rather than mere occasional abstinence from food.

From Manners and Customs of the Bible:

It is said that these semi-weekly fasts were observed by the Jews because continuous fasting might be injurious. The clays selected were the second and fifth. The reason assigned for the selection of these days is because it was supposed to be on the second day of the week that Moses went up into Mount Sinai to receive the two tables of the law, and it was on the fifth day of the week that he came down on account of the idolatry concerning the golden calf. These days were chosen, not only when public tarts were to be observed, but also when individuals fasted privately.