Westminster Confession Of Faith – Lord’s Day 37
Chapter 22 – Of Lawful Oaths and Vows (Paragraphs 1-3)
I. A lawful oath is a part of religious worship, wherein upon just occasion, the person swearing solemnly calls God to witness what he asserts or promises; and to judge him according to the truth or falsehood of what he swears.
II. The name of God only is that by which men ought to swear, and therein it is to be used with all holy fear and reverence; therefore to swear vainly or rashly by that glorious and dreadful name, or to swear at all by any other thing, is sinful, and to be abhorred. Yet, as, in matters of weight and moment, an oath is warranted by the Word of God, under the New Testament, as well as under the Old, so a lawful oath, being imposed by lawful authority, in such matters ought to be taken.
III. Whosoever takes an oath ought duly to consider the weightiness of so solemn an act, and therein to avouch nothing but what he is fully persuaded is the truth. Neither may any man bind himself by oath to any thing but what is good and just, and what he believes so to be, and what he is able and resolved to perform. Yet it is a sin to refuse an oath touching anything that is good and just, being imposed by lawful authority.