'As the Lord Lives' in the Bible

And David answered Rechab and Baanah his brother, the sons of Rimmon the Beerothite, and said unto them, As the LORD lives, who has redeemed my soul out of all adversity,

And David's anger was greatly kindled against the man; and he said to Nathan, As the LORD lives, the man that has done this thing shall surely die:

Then said she, I pray you, let the king remember the LORD your God, that you would not allow the revengers of blood to destroy any more, lest they destroy my son. And he said, As the LORD lives, there shall not one hair of your son fall to the earth.

And Ittai answered the king, and said, As the LORD lives, and as my lord the king lives, surely in what place my lord the king shall be, whether in death or life, even there also will your servant be.