Do you know how critical spoken words can be? For instance, volumes could be written about the very first verse in Numbers 30, where we see YHWH's instructions regarding the making of vows.
Numbers 30: 1 Then Moshe spoke to the heads of the tribes of the people of Isra'el. He said, "Here is what ADONAI has ordered: 2 when a man makes a vow to ADONAI or formally obligates himself by swearing an oath, he is not to break his word but is to do everything he said he would do. (CJB)
YHWH takes oaths very seriously, especially ones that were made to Him! Today, contracts don't seem to hold any meaning anymore because, many believe contracts were made to be broken and/or re-written to suit a certain purpose. Even many couples who are married in church and pledged to stay together "unto death" demonstrate instead that they didn’t take their oath very seriously, and end up divorced.
Unbeknownst to them, the vows made before YHWH stand, regardless! YHWH doesn't care what the reasoning, whether simple carnal desire or profit of some kind. A contract is a contract. (Yes, there are certain grounds for divorce, according to Torah, but every effort must be made to restore the marriage, first.) We are to hold to our word. Scripture tells us that every word that comes from our mouth has consequences!
Remember the story about Bil'am in Numbers 22-24, who was originally hired to put a curse on Israel, but was ultimately forced to do YHWH's will, instead? Well, check out Numbers 31:8 which tells us he was killed by the sword! Bil'am was NOT a good man, and YHWH intervened to use for good what Bil'am had originally meant for evil.
Words...oaths...curses. We are told to guard our mouths and even to take every thought captive (Psalm 141:3, Proverbs 21:23, 2 Corinthians 10:5, etc).