'Swear' in the Bible

In that day there shall be five cities in the land of Egypt that speak the language of Canaan, and swear to Jehovah of hosts; one shall be called The city of destruction.

By myself have I sworn, the word is gone forth from my mouth in righteousness, and shall not return, that unto me every knee shall bow, every tongue shall swear.

Hear ye this, O house of Jacob, who are called by the name of Israel, and are come forth out of the waters of Judah; who swear by the name of Jehovah, and make mention of the God of Israel, but not in truth, nor in righteousness.

so that he who blesseth himself in the earth shall bless himself in the God of truth; and he that sweareth in the earth shall swear by the God of truth; because the former troubles are forgotten, and because they are hid from mine eyes.