A solemn promise made to God to perform some act, make some offering or gift, enter some service or condition, or abstain from certain things not unlawful in themselves. A vow was a voluntary expression made of one’s own free will. Being a solemn promise, a vow carried the force of an oath or a swearing, and at times the two expressions accompany each other in the Bible. (Nu 30:2; Mt 5:33) “Vow” is more the declaration of intent, while “oath” denotes the appeal made to a higher authority attesting to the truthfulness or binding nature of the declaration. Oaths often accompanied attestation to a covenant.​—Ge 26:28; 31:44, 53.

The earliest record of a vow is found at Genesis 28:20-22, where Jacob promised to give Jehovah one tenth of all his possessions if Jehovah would continue with him and bring him back in peace, thereby proving to be Jacob’s God. Jacob was not bargaining with God, but he wanted to be sure that he had God’s approval. As this example points out, vows were made by the patriarchs (see also Job 22:27), and as with so many other patriarchal customs, the Mosaic Law, rather than introduce these already-existing features of worship, defined and regulated them.

Many vows were made as appeals to God for his favor and success in an undertaking, as in Jacob’s case. Another example of such is the vow by Israel to devote the cities of the Canaanite king of Arad to destruction if Jehovah gave Israel the victory. (Nu 21:1-3) Vows were also made as expressions of devotion to Jehovah and his pure worship (Ps 132:1-5) or to indicate that a person was setting himself or his possessions apart for special service. (Nu 6:2-7) Parents could make vows in connection with their children, as Hannah did regarding Samuel. (1Sa 1:11; compare Jg 11:30, 31, 39.) In these instances the children cooperated in carrying out the vow.

Voluntary, but Binding When Once Made. Vows were wholly voluntary. However, once a man made a vow, fulfillment was compulsory by divine law. Thus a vow was spoken of as being ‘bound upon his soul,’ implying that his very life became surety for the performance of his word. (Nu 30:2; see also Ro 1:31, 32.) Since life is at stake, it is understandable why the Scriptures urge one to use extreme caution before making a vow, carefully considering the obligations to be assumed. The Law stated: “In case you vow a vow to Jehovah . . . God will without fail require it of you, and it would indeed become a sin on your part. But in case you omit making a vow, it will not become a sin on your part.”​—De 23:21, 22.

As later expressed by the Congregator: “What you vow, pay. Better is it that you vow not than that you vow and do not pay. Do not allow your mouth to cause your flesh to sin, neither say before the angel that it was a mistake.” (Ec 5:4-6) A vow rashly made on the impulse of momentary enthusiasm or mere emotion might very well prove to be a snare. (Pr 20:25) Under the Law one making such a thoughtless vow was guilty before God and had to present a guilt offering for his sin. (Le 5:4-6) In the final analysis, a vow has no merit in the eyes of God unless it is in harmony with his righteous laws and issues from the right kind of heart and spirit.​—Ps 51:16, 17.

Vows of women, under the Law. The laws regulating vows made by women are outlined at Numbers 30:3-15: The vow of a daughter was binding once her father heard it and raised no objection; or, instead, he could annul it. The vow of a wife (or an engaged girl) likewise depended on her husband (or fiancé) for validation. If the man annulled the vow after first letting it stand, he bore her error. (Nu 30:14, 15) In the case of a widow or a divorced woman, “everything that she has bound upon her soul will stand against her.”​—Nu 30:9.

Disposition of Things Vowed. In fulfillment of a vow, any person or possession, including land, could be offered to Jehovah, except what had already been set apart for Him by the Law​—the firstborn, firstfruits, tithes, and the like. (Le 27:26, 30, 32) That which was vowed as “sanctified” (Heb., qoʹdhesh, something set aside as holy, for sacred use) could be redeemed by a certain payment  to the sanctuary (except clean animals). (Le 27:9-27) However, anything “devoted” (Heb., cheʹrem) could not be redeemed, but it was to be completely and permanently the property of the sanctuary or, if devoted to destruction, was to be destroyed without fail.​—Le 27:28, 29.

Wrong or Unclean Vows. The vows of heathen religions many times involved unclean, immoral practices. Throughout Phoenicia, Syria, and Babylon, the proceeds of temple prostitution were dedicated to the idol or temple. Such degenerate vows were outlawed in Israel: “You must not bring the hire of a harlot or the price of a dog [likely, a pederast (sodomite)] into the house of Jehovah your God for any vow.”​—De 23:18, ftn.

After Jerusalem’s destruction, Jeremiah reminded the Jews in Egypt that one reason for the calamity that befell them was their making vows to the “queen of the heavens” and offering sacrifices to her. The women who were taking a prominent part in this idol worship were quick to point out that their vows and worship to the “queen of the heavens” had been approved by their husbands and that they were determined to carry out their vows to this goddess. They thus made the excuse that they were acting in harmony with the Law regarding vows for women (Nu 30:10-15), but Jeremiah denounced their actions as being really law defying, since they were idolatrous.​—Jer 44:19, 23-25; 2Co 6:16-18.

Hypocritical vows. The Jews did not slip back into outright idol worship after the exile. However, they “made the word of God invalid because of [their] tradition.” Their specious reasoning in interpreting the Law affected the matter of vows as well as other features of worship, their religious leaders hypocritically teaching “commands of men as doctrines.” (Mt 15:6-9) For example, Jewish tradition stated that if a man said to his father or mother, “Whatever I have by which you might get benefit from me is a gift dedicated to God” (a pronouncement of dedication or sanctification), he thereby vowed to sanctify all he had spoken of to God and was not to use these things to help his parents; this was on the theory that now the temple had the prior claim to these possessions, although he was actually allowed full liberty to keep them for himself.​—Mt 15:5, 6.

Sacrifices Connected With Vows. Under the Law, a burnt offering at times accompanied other sacrifices, to denote complete dedication and an appeal to Jehovah to accept the sacrifice with favor. (Le 8:14, 18; 16:3) Such was true in connection with vows. (Nu 6:14) Burnt offerings were sacrificed to perform special vows. (Nu 15:3; Ps 66:13) And concerning a “communion sacrifice to Jehovah in order to pay a vow,” the requirement was that an unblemished animal be offered, part of which was burned on the altar.​—Le 22:21, 22; 3:1-5.

As regards Jephthah’s vow before fighting the Ammonites (Jg 11:29-31), see JEPHTHAH.

Paul’s Observance of Law as to Vows. The apostle Paul made a vow, whether a Nazirite vow or not is uncertain; also, whether he had made the vow before becoming a Christian is not stated. He may have concluded the period of his vow at Cenchreae, near Corinth, when he had his hair clipped (Ac 18:18) or, as some believe, when he went to the temple in Jerusalem with four other men who were completing their vows. However, this latter action was taken by Paul on the advice of the Christian governing body to demonstrate that Paul was walking orderly and not teaching disobedience to the Law, as rumored in the ears of some of the Jewish Christians. It was common practice for a person to pay for others the expenses involved in the ceremonial cleansing at the expiration of the period of a vow, as Paul here did.​—Ac 21:20-24.

As to why the apostle Paul and his associates in the Christian governing body approved the carrying out of certain features of the Law, even though the Law had been moved out of the way by the sacrifice of Jesus Christ, the following things may be considered: The Law was given by Jehovah God to his people Israel. Accordingly, the apostle Paul said, “The Law is spiritual,” and of its regulations he said, “The Law is holy, and the commandment is holy and righteous and good.” (Ro 7:12, 14) Consequently, the temple and the services carried on there were not despised by Christians, or looked down upon as wrong. They were not idolatrous. Furthermore, many of the practices had become ingrained as custom among those who were Jews. Moreover, since the Law was not merely religious but was also the law of the land, some things, such as the restrictions on work on the Sabbaths, had to be followed by all those living in the land.

But in considering this matter, the main point is that the Christians did not look to these things for salvation. The apostle explained that certain things, such as the eating of meat or vegetables, the observing of certain days as above others, even the eating of meat that had been offered to idols before being put up for regular sale in the marketplaces, were matters of conscience. He wrote: “One man judges one day as above another; another man judges one day as all others; let  each man be fully convinced in his own mind. He who observes the day observes it to Jehovah. Also, he who eats, eats to Jehovah, for he gives thanks to God; and he who does not eat does not eat to Jehovah, and yet gives thanks to God.” Then he summed up his argument by stating the principle: “For the kingdom of God does not mean eating and drinking, but means righteousness and peace and joy with holy spirit,” and he concluded: “Happy is the man that does not put himself on judgment by what he approves. But if he has doubts, he is already condemned if he eats, because he does not eat out of faith. Indeed, everything that is not out of faith is sin.”​—Ro 14:5, 6, 17, 22, 23; 1Co 10:25-30.

An enlightening comment is made on this point by Bible scholar Albert Barnes, in his Notes, Explanatory and Practical, on the Acts of the Apostles (1858). Making reference to Acts 21:20​—which reads: “After hearing this [an account of God’s blessing on Paul’s ministry to the nations] they began to glorify God, and they said to him: ‘You behold, brother, how many thousands of believers there are among the Jews; and they are all zealous for the Law’”​—Barnes remarks: “The reference here is, to the law respecting circumcision, sacrifices, distinctions of meats and days, festivals, &c. It may seem remarkable that they should still continue to observe those rites, since it was the manifest design of Christianity to abolish them. But we are to remember, (1.) That those rites had been appointed by God, and that they were trained to their observance. (2.) That the apostles conformed to them while they remained in Jerusalem, and did not deem it best to set themselves violently against them. [Ac 3:1; Lu 24:53] (3.) That the question about their observance had never been agitated at Jerusalem. It was only among the Gentile converts that the question had risen, and there it must arise, for if they were to be observed, they must have been imposed upon them by authority. (4.) The decision of the council (ch. xv.) related only to the Gentile converts. [Ac 15:23] . . . (5.) It was to be presumed, that as the Christian religion became better understood​—that as its large, free, and [universal] nature became more and more developed, the peculiar institutions of Moses would be laid aside of course, without agitation, and without tumult. Had the question been agitated [publicly] at Jerusalem, it would have excited tenfold opposition to Christianity, and would have rent the Christian church into factions, and greatly retarded the advance of the Christian doctrine. We are to remember also, (6.) That, in the arrangement of Divine Providence, the time was drawing near which was to destroy the temple, the city, and the nation; which was to put an end to sacrifices, and effectually to close for ever the observance of the Mosaic rites. As this destruction was so near, and as it would be so effectual an argument against the observance of the Mosaic rites, the Great Head of the church did not suffer the question of their obligation to be needlessly agitated among the disciples at Jerusalem.”