'Swear' in the Bible

In that day shall he swear, saying, I will not be an healer; for in my house is neither bread nor clothing: make me not a ruler of the people.

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

I have sworn by myself, the word is gone out of 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, which are called by the name of Israel, and are come forth out of the waters of Judah, which swear by the name of the LORD, and make mention of the God of Israel, but not in truth, nor in righteousness.

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.