Chapter 23 — Of Lawful Oaths and Vows
Section 6. It is not to be made to any creature, but to God alone; and that it may be accepted, it is to be made voluntarily, out of faith and conscience of duty, in way of thankfulness for mercy received, or for obtaining of what we want; whereby we more strictly bind ourselves to necessary duties, or to other things, so far and so long as they may fitly conduce thereunto.