'Sware' in the Bible

And Saul hearkened unto the voice of Jonathan: and Saul sware, As the LORD liveth, he shall not be slain.

And David sware moreover, and said, Thy father certainly knoweth that I have found grace in thine eyes; and he saith, Let not Jonathan know this, lest he be grieved: but truly as the LORD liveth, and as thy soul liveth, there is but a step between me and death.

And David sware unto Saul. And Saul went home; but David and his men gat them up unto the hold.

And Saul sware to her by the LORD, saying, As the LORD liveth, there shall no punishment happen to thee for this thing.