Westminster Confession of Faith 22.4

Chapter 22 — Of Lawful Oaths and Vows

Section 4. An oath is to be taken in the plain and common sense of the words, without equivocation or mental reservation. It cannot oblige to sin; but in any thing not sinful, being taken, it binds to performance, although to a man's own hurt; nor is it to be violated, although made to heretics or infidels.