De Decalogo

By the third commandment he restrains people from taking oaths, and limits the objects for which one may swear, defining when and where it may be lawful, and who may swear, and how the swearer ought to be disposed, both in his soul and body, and many other minute particulars, concerning those who keep their oaths, and the contrary.

And the fourth commandment, the one about the seventh day, we must not look upon in any other light than as a summary of all the laws relating to festivals, and of all the purificatory rites enjoined to be observed on each of them. But the service appointed for them was one of holy ablutions, and prayers deserving to be heard, and perfect sacrifices.