Numbers 30:2

The tribal leaders. He bestowed honor on the leaders by teaching them first, and afterward, all of Bnei Yisroel. How do we know that the other discourses were so? The Torah therefore teaches, “. . . they returned to him— Aharon and all the leaders of the congregation— and Moshe spoke to them. Afterward, all of Bnei Yisroel approached.” Why, then, did he see fit to say this here? He taught that vows may be nullified by a single expert. When there is no single expert, nullification is by three laymen. But perhaps Moshe recited this chapter only to the leaders? “This is the word” is said here, and it is said concerning slaughtering outside [the Temple], “this is the word.” Just as that was said to Aharon and his sons, and all of Bnei Yisroel, as it is said, “speak to Aharon, etc.,” so was this, said to all of them.

This is the word. Moshe prophesied with “this is what Adonoy has said, about the time of midnight. . .,” and the [other] prophets prophesied with “this is what Adonoy has said:” Moshe surpassed them, as he prophesied with the phrase “this is the word.” Another interpretation: “This is the word” is exclusionary, teaching that the Sage [annuls] with the term “release,” and the husband with the term “nullification,” following the Scriptural language here. If they reverse the terminology, there is neither release nor nullification.

AND Mosheh spake with the chiefs of the Tribes of the Beni Israel, saying: This is the Word which the Lord hath spoken, saying:

The heads of the tribes: According to my opinion that this section is after the war with Midian, it is for this reason that [the section about that war] is after it; just as "And Miriam and Aaron spoke about Moses (Numbers 12:1) is after "and they were in Chatserot" (Numbers 11:35) [even though it happened earlier], as I explained.1 And Scripture states that the Children of Gad came to Moses and Elazar and the princes of the congregation and they spoke their words. And afterwards, it is written (Numbers 32:28), "Then Moses gave instructions concerning them to Elazar the priest, Joshua son of Nun, and the family heads of the Israelite tribes" - which are the princes of the congregation [just] mentioned. And since Moses said to the Children of Gad and the Children of Reuben (Numbers 32:24), "you shall do what comes out of your mouth"; it is therefore written (Numbers 30:2), "And Moses spoke to the heads of the tribes," and then (verse 3), "he shall do like everything that comes out of his mouth."

AND MOSES SPOKE UNTO THE HEADS OF THE TRIBES. Scripture did not precede this section with [the statement]: “And the Eternal spoke unto Moses, saying: Speak unto the heads of the tribes, and say unto them: This is the thing which the Eternal hath commanded,” as He stated in the section [dealing with] slaughtering [offerings] outside the Sanctuary Court, and in other sections. Instead, He mentioned it as the end of this section, saying, These are the statutes, which the Eternal commanded Moses. And in the section of Vayehi Bayom Ha’shemini it says: And Moses said: ‘This is the thing which the Eternal commanded that ye should do,’, Verse 6. See also Ramban ibid. Verse 2. but did not mention the [actual] command [given by G-d to Moses] at all. Similarly, in the section about the manna [it is said], And Moses said: ‘This is the thing which the Eternal hath commanded: Let an omerful of it be kept etc.’ [although the Divine command about it to Moses is not expressly stated].
Now the heads of the tribes of the children of Israel are the princes of the standards, whom the tribes had appointed over their standards after Nachshon the son of Amminadab [prince of the children of Judah] and his colleagues had died. It is possible that they [the heads of the tribes referred to here] were those who are mentioned in the section [dealing with] the inheritance [of the Land]: These are the names of the men that shall take possession of the Land for you; or it may be that those [referred to here] were others, for there Scripture speaks about [the leaders of] the future [saying] that when they come to divide up the Land [in the time of Joshua] all those mentioned will be living, and they will represent them [in the apportionment of the Land].
And Moses spoke unto the heads of the tribes. The reason [why he did not address this section to the entire people] is because it was not necessary to teach all the children of Israel that the father and husband [of a woman] can declare void those vows [of their daughter or wife, respectively] which involve affliction of the soul, and perhaps it is [even] necessary to conceal these [rights] from them, so that they should not treat vows lightly. But it was to the Sages of Israel, the heads of their tribes, that he taught the ordinance [of vows]. The verse also alludes to the interpretation of our Rabbis [who said] that the heads of the tribes have a …

וידבר משה אל ראשי המטות, I was asked by people in some town in France, Anyon, where else we find a portion commencing with the words וידבר משה, without being told first that G’d had told Moses to deliver the message or legislation in question to the people. My answer to the question was that we had read in Numbers 29,39 אלה תעשו לה' במועדיכם לבד מנדריכם ומנדבותיכם, “These you are to present to the Lord,” i.e. sacrifices which you have to present on one of the three pilgrimage festivals, seeing that everyone who is tardy is guilty of a serious misdemeanour, as we know from Rosh Hashanah 4. It was no more than natural that after he heard this Moses went and told the heads of the tribes, the judges all the details pertaining to all kinds of vows, including those between husband and wife, etc.

The words איש כי ידור נדר, refer to a person vowing to bring a voluntary sacrifice, just as the words או השבע שבועה mean that he phrases this vow in a negative manner. When the Torah adds that such a person must not יחל his word, the meaning is that he must not be late in fulfilling his vow else he is considered as having broken his promise, i.e. delay carrying out his word, his promise. He has only until (according to one view) the next pilgrimage festival to come to Jerusalem and make good on his vow. Seeing that at that time he must come to Jerusalem at any event, this does not impose any kind of hardship on him. The expression יחל in the sense of delaying, procrastinating, occurs several times in Scripture, for instance in Judges 3,25 ויחל עד בוש, “he waited an embarrassingly long time.” Or, in Genesis 8,10 ויחל עוד שבעת ימים, we read that Noach waited another seven days before sending out the dove again. In Psalms 130,7 David speaks of יחל ישראל אל ה', meaning that Israel is to continue to wait for G’d hopefully. Anyone translating the words לא יחל דברו as “he must not profane, dishonour his word,” as the plain meaning of the verse is in error.

'וידבר משה אל ראשי המטות....זה הדבר אשר צוה ה, G’d had commanded the basic legislation at Mount Sinai when He had said (Leviticus 19,12) ולא תשבעו בשמי לשקר וחללת וגו' “do not render a false oath in My name and thereby desecrate it.” The plain meaning of that verse had not been that you must not deliberately swear falsely, but that having sworn you must honour your oath in all its details. A woman who is married and therefore subject to restrictions imposed upon her by the authority of her husband, is not considered as having desecrated G’d’s name when violating her vows or oath on that account, provided her husband had declared her vow void.

וידבר משה אל ראשי המטות וגו'...זה הדבר אשר צוה ה,“Moses spoke to the heads of the tribes of Israel....this is what the Lord has commanded.” When Rabbi Sh’muel son of Meir, a grandson of Rashi, was asked where we can find that the legislation concerning vows was commanded to Moses, he directed the questioner to what has been written in the Torah immediately prior to our portion, namely: “these are the rules concerning the festivals for the Lord, apart from your vows, etc. “(Numbers, 29 39) The reference is to free willed vows and free will offerings, etc. There is also another category of vows, which is discussed in the Torah. Our verse refers to the chapter 28 in Numbers which commences with rules concerning sacrificial offerings.