'Vowed' in the Bible

Saul listened to the voice of Jonathan, and Saul vowed, “As the Lord lives, he shall not be put to death.”

Yet David vowed again, saying, “Your father knows well that I have found favor in your sight, and he has said, ‘Do not let Jonathan know this, or he will be grieved.’ But truly as the Lord lives and as your soul lives, there is hardly a step between me and death.”

Saul vowed to her by the Lord, saying, “As the Lord lives, no punishment shall come upon you for this thing.”