Paragraph 23.2
Of the Second London Baptist Confession of Faith
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;1 yet as in matter of weight and moment, for confirmation of truth, and ending all strife, an oath is warranted by the Word of God;2 so a lawful oath being imposed by lawful authority in such matters, ought to be taken.3
The Westminster Confession of Faith (1646)
22.2
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;1 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.2 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,3 so a lawful oath, being imposed by lawful authority, in such matters ought to be taken.4