'Invalid' in the Bible

if a man makes a vow for Yahweh or swears an oath with a binding pledge on himself, he must not render his word invalid; he must do all that went out from his mouth.

The man’s name was Elimelech and his wife’s name was Naomi and his two sons were named Mahlon and Chilion. They were Ephrathites from Bethlehem in Judah. They went to the country of Moab and stayed there.