Note: These were my notes for Parshat Mattot-Maasei.  The spoken version rarely coincides with what I wrote, but it should give you an idea of my thought process!
וַיְדַבֵּ֤ר מֹשֶׁה֙ אֶל־רָאשֵׁ֣י הַמַּטּ֔וֹת לִבְנֵ֥י יִשְׂרָאֵ֖ל לֵאמֹ֑ר זֶ֣ה הַדָּבָ֔ר אֲשֶׁ֖ר צִוָּ֥ה Hashem׃
Moses spoke to the heads of the Israelite tribes, saying: This is what the LORD has commanded:
אִישׁ֩ כִּֽי־יִדֹּ֨ר נֶ֜דֶר לַֽHashem אֽוֹ־הִשָּׁ֤בַע שְׁבֻעָה֙ לֶאְסֹ֤ר אִסָּר֙ עַל־נַפְשׁ֔וֹ לֹ֥א יַחֵ֖ל דְּבָר֑וֹ כְּכָל־הַיֹּצֵ֥א מִפִּ֖יו יַעֲשֶֽׂה׃
If a man makes a vow to the LORD or takes an oath imposing an obligation on himself, he shall not break his pledge; he must carry out all that has crossed his lips.

Our parsha opens with these sacred words.  The rabbis are very concerned about vows and oaths.  They strongly discourage us from taking them, noting in the Talmud that the Nazir, like Samson, the one who refuses hair cuts and wine, must offer a sin offering at the end of his vow.  The following verses detail how women’s vows are limited; that fathers and husbands can annul their daughters’ and spouses’ vows.  While patriarchal and seemingly sexist, it shows a deep discomfort with the concept of vows themselves.

While in other weeks, I have spoke about the concept of shalom bayit, of peace in the home, and how that might seem to occasionally supercede complete honesty; the arc of our tradition shows us over and over again that words matter.  Unlike many of our politicians who seem not to know truth if it smacks them in the face, who make campaign promises they have no intention of keeping, our Torah teaches us that our word must be true.

Words are incredibly powerful.  According to Bershit, it is with words that the Holy One created this world.  There are Talmudic stories of people who throw themselves in fiery furnaces to avoid embarrassing another person with their words.  There are many books on Lashon Hara and Motzi Shem Ra, discouraging us from gossip or even sharing painful truths about one another–words are powerful.  All these books show us that even a flippant comment can be dangerous to the wellbeing of others–I know I can be guilty of this!

I have been told that in the diamond district, many deals are sealed with a handshake and a “Mazel and Brocha”.  No contract need be signed, because the trust in that community is so strong, the word of one Jew to another is inviolable.  While I cannot attest to the reliability of those deals, I have heard that these words are stronger than any contract.  Is the same true for us? 
This week we conclude the wanderings in the wilderness.  Next week we read from Devarim, as Moshe Rabbenu will help us be sure of our commands before we enter the land.  The parsha opens with concerns about vows, with concerns about words and their power.  As we prepare to enter Israel, we are envisioning a perfect society.  As such we are building it peacefully with a reminder of the importance of the truth!  We must be honest!