'Swear' in the Bible

In that day, there will be five cities in the land of Egypt that speak the language of Canaan, and swear to Yahweh of Armies. One will be called "The city of destruction."

"Hear this, house of Jacob, you who are called by the name of Israel, and have come forth out of the waters of Judah; who swear by the name of Yahweh, and make mention of the God of Israel, but not in truth, nor in righteousness

so that he who blesses himself in the earth shall bless himself in the God of truth; and he who swears in the earth shall swear by the God of truth; because the former troubles are forgotten, and because they are hidden from my eyes.