| Barnes' Notes on the Bible The regulations respecting vows appropriately follow those given respecting sacrifices, since a large proportion of vows would always relate to the presentation of such offerings. Rules had already been given Leviticus 27 for the estimation of things vowed to God. It is probable that this fresh legislation dealing especially with vows made by persons in a state of tutelage, was occasioned by some case of practical difficulty that had recently arisen; and it is addressed by Moses to "the heads of the tribes" Numbers 30:1, who would in their judicial capacity have to determine questions on these subjects. There is no provision in the chapter for annulling vows made by boys and young men; from which it has been inferred that the vows of males were in all cases and circumstances binding.
Gill's Exposition of the Entire BibleAnd Moses spake unto the heads of the tribes,.... Or the princes of them, who could more easily be convened, and who used to meet on certain occasions, and on whom it lay to see various laws put in execution: concerning the children of Israel; how they ought to conduct and behave in the following case, it being an affair which concerned them all: saying, this is the thing which the Lord hath commanded; relating to vows. Aben Ezra is of opinion that this was delivered after the battle with Midian, of which there is an account in the following chapter, and is occasioned by what was said, to the tribes of Gad and Reuben, Numbers 32:24. do that which hath proceeded out of your mouth; to which they replied: thy servants will do as my lord commandeth; upon which the nature of a vow, and the manner of keeping it, are observed; but the occasion of it rather seems to be what is said towards the close of the foregoing chapter, Numbers 29:39, that the various sacrifices there directed were to be offered in their season, besides the vows and freewill offerings; and when these were ratified and confirmed, and when null and void, and to be fulfilled or neglected, is the principal business of this chapter.
Keil and Delitzsch Biblical Commentary on the Old TestamentThe rules by which vows were to be legally regulated, so far as their objects and their discharge were concerned, has been already laid down in Lev; but the chapter before us contains instructions with reference to the force of vows and renunciations. These are so far in place in connection with the general rules of sacrifice, that vows related for the most part to the presentation of sacrifices; and even vows of renunciation partook of the character of worship. The instructions in question were addressed (Numbers 30:1) to "the heads of the tribes," because they entered into the sphere of civil rights, namely, into that of family life.
Geneva Study BibleAnd Moses spake unto the heads of the tribes {a} concerning the children of Israel, saying, This is the thing which the LORD hath commanded. (a) Because they might declare them to the Israelites.
Jamieson-Fausset-Brown Bible CommentaryCHAPTER 30 Nu 30:1-16. Vows Are Not to Be Broken. 1. This is the thing which the Lord hath commanded-The subject of this chapter relates to vowing, which seems to have been an ancient usage, allowed by the law to remain, and by which some people declared their intention of offering some gift on the altar or abstaining from particular articles of meat or drink, of observing a private fast, or doing something to the honor or in the service of God, over and above what was authoritatively required. In Nu 29:39, mention was made of "vows and freewill offerings," and it is probable, from the explanatory nature of the rules laid down in this chapter, that these were given for the removal of doubts and difficulties which conscientious persons had felt about their obligation to perform their vows in certain circumstances that had arisen.
Matthew Henry's Concise Commentary30:1,2 No man can be bound by his own promise to do what he is already, by the Divine precept, forbidden to do. In other matters the command is, that he shall not break his words, through he may change his mind.
Matthew Henry's Whole Bible CommentaryChapter 30 In this chapter we have a law concerning vows, which had been mentioned in the close of the foregoing chapter. I. Here is a general rule laid down that all vows must be carefully performed (v. 1, 2). II. Some particular exceptions to this rule. 1. That the vows of daughters should not be binding unless allowed by the father (v. 3-5). Nor, 2. The vows of wives unless allowed by the husband (v. 6, etc.). Verses 1-2 This law was delivered to the heads of the tribes that they might instruct those who were under their charge, explain the law to them, give then necessary cautions, and call them to account, if there were occasion, for the breach of their vows. Perhaps the heads of the tribes had, upon some emergency of this kind, consulted Moses, and desired by him to know the mind of God, and here they are told it: This is the thing which the Lord has commanded concerning vows, and it is a command still in force. 1. The case supposed is that a person vows a vow unto the Lord, making God a party to the promise, and designing his honour and glory in it. The matter of the vow is supposed to be something lawful: no man can be by his own promise bound to do that which he is already by the divine precept prohibited from doing. Yet it is supposed to be something which, in such and such measures and degrees, was not a necessary duty antecedent to the vow. A person might vow to bring such and such sacrifices at certain times, to give such and such a sum or such a proportion in alms, to forbear such meats and drinks which the law allowed, to fast and afflict the soul (which is specified v. 13) at other times besides the day of atonement. And many similar vows might be made in an extraordinary heat of holy zeal, in humiliation for some sin committed or for the prevention of sin, in the pursuit of some mercy desired or in gratitude for some mercy received. It is of great use to make such vows as these, provided they be made in sincerity with due caution. Vows (say the Jewish doctors) are the hedge of separation, that is, a fence to religion. He that vows is here said to bind his soul with a bond. It is a vow to God, who is a spirit, and to him the soul, with all its powers, must be bound. A promise to man is a bond upon the estate, but a promise to God is a bond upon the soul. Our sacramental vows, by which we are bound to no more than what was before our duty, and which neither father nor husband can disannul, are bonds upon the soul, and by them we must feel ourselves bound out from all sin and bound up to the whole will of God. Our occasional vows concerning that which before was in our own power (Acts 5:4), when they are made, are bonds upon the soul likewise. 2. The command given is that these vows be conscientiously performed: He shall not break his word, though afterwards he may change his mind, but he shall do according to what he has said. Margin, He shall not profane his word. Vowing is an ordinance of God; if we vow in hypocrisy we profane that ordinance: it is plainly determined, Better not vow than vow and not pay, Eccl. 5:5. Be not deceived, God is not mocked. His promises to us are yea and amen, let not ours to him be yea and nay. | 
