Parshas Matos begins with the laws regarding one who makes a neder or a shevua: "A man who takes a vow to Hashem or swears an oath . . . he shall not desecrate his word, whatever comes out of his mouth he must fulfill" (Bamidbar 30, 3). Rav Wolbe (Shiurei Chumash) quotes Rav Yeruchom Levovitz who would say that from this parsha we can glean the greatness of man. A person has the ability to create a prohibition with an utterance of his lips! His very words obligate him in a manner no different than the rest of the mitzvos of the Torah. Should he fail to fulfill this obligation, says the Torah, he has desecrated something holy.
The idea is presented very clearly by the Rambam. He writes (Hilchos Me'ilah), "Wood and stones, dirt and ash; once the name of the Master of the World is proclaimed upon them with mere words, they have become holy and one who uses them in a mundane fashion has profaned [something holy]." It is incredible to think that the basest objects turn into an object of kedusha when one, by way of his words, donates them to the Beis Hamikdosh.
How does a human have such an awesome ability? How can his words be so powerful? Every Jew has a neshama which was given to him from on high and connects him to the source of all kedusha, and it is so great and holy that we cannot truly comprehend just how awesome it really is. It is via this holy neshama that one can draw on the wellsprings of kedusha, and with a declaration of his mouth he can change sticks and stones into objects of holiness! (Da'as Shlomo)
Let us not forget just how great we really are. Our words are powerful. Not only do they have the ability to create Torah prohibitions, they have the ability to change the mechanism of the world through our tefillos and our Torah learning. We have such a powerful storehouse of ammunition; it would be a waste not to use it! Israel is at war and every prayer is vital. The truth is that we should implore Hashem to send Moshiach, and then all of our issues will be resolved. There is no better time than the three weeks to beseech Hashem that He have compassion on us bring about the Geulah Shleimah bimheira b'yameinu!