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.
נדר. הָאוֹמֵר הֲרֵי עָלַי קוֹנָם שֶׁלֹּא אֹכַל אוֹ שֶׁלֹּא אֶעֱשֶׂה דָבָר פְּלוֹנִי; יָכוֹל אֲפִלּוּ נִשְׁבַּע שֶׁיֹּאכַל נְבֵלוֹת אֲנִי קוֹרֵא עָלָיו כְּכָל הַיֹּצֵא מִפִּיו יַעֲשֶׂה? תַּ"ל לאסר אסר — לֶאֱסֹר אֶת הַמֻּתָּר וְלֹא לְהַתִּיר אֶת הָאָסוּר (ספרי):
נדר A VOW — This is when one says, Behold, I take upon myself an obligation which is as sacred to me as an offering, that I will not eat, or that I will not do such-and-such a thing. — One might think that if he swears that he will eat the flesh of an animal which has not been slaughtered properly according to the rite that I may apply to him the text, “He shall do according to all that goeth forth from his mouth”! It, however, says, “[If he takes an oath] to forbid something to himself”, i.e., to forbid for himself something which is permissible to him — and not to make permissible that which is forbidden to him (Sifrei Bamidbar 153:4).
Words have power - they can make something muttar into something assur, and promises are binding; there are complex halachos that govern undoing a promise. What are some ways you can use to make sure you always keep your word?
Jewish people's main weapon is their speech. Even the wisest warrior can't fight them without utilizing this power. It is something "given to them as a gift, capable of creating heaven and earth." When people speak words of holiness, they create worlds and they create angels, and people must be extremely careful not to damage this gift through forbidden speech, lashon harah, and rechilus.
How can you use your power of speech for good? How might someone use it for bad? How can you avoid using it for bad things?
What can you do to avoid talking lashon harah and use your power of speech in the best way possible?