'Sware' in the Bible

So Zedekiah the king sware secretly unto Jeremiah, saying, As the LORD liveth, that made us this soul, I will not put thee to death, neither will I give thee into the hand of these men that seek thy life.

And Gedaliah the son of Ahikam the son of Shaphan sware unto them and to their men, saying, Fear not to serve the Chaldeans: dwell in the land, and serve the king of Babylon, and it shall be well with you.