Concerning the Ten Commandments, which are the Heads of the Law (83-85)

Having, therefore, previously spoken of the existence of God, and also of the honour to be paid to the everlasting God; he then, following the natural order of connection proceeds to command what is becoming in respect of his name; for the errors of men with respect to this point are manifold and various, and assume many different characters.

That being which is the most beautiful, and the most beneficial to human life, and suitable to rational nature, swears not itself, because truth on every point is so innate within him that his bare word is accounted an oath. Next to not swearing at all, the second best thing is to keep one’s oath; for by the mere fact of swearing at all, the swearer shows that there is some suspicion of his not being trustworthy.

Let a man, therefore, be dilatory, and slow if there is any chance that by delay he may be able to avoid the necessity of taking an oath at all; but if necessity compels him to swear, then he must consider with no superficial