John Chrysostom : Wherefore when He speaks to us of another commandment, not known to us by the dictate of conscience, He not only prohibits, but adds the reason. When, for instance, He gave commandment respecting the Sabbath; "On the seventh day thou shalt do no work;" He subjoined also the reason for this cessation. What was this? "Because on the seventh day God rested from all His works which He had begun to make." And again; "Because thou wert a servant in the land of Egypt." For what purpose then I ask did He add a reason respecting the Sabbath, but did no such thing in regard to murder? Because this commandment was not one of the leading ones. It was not one of those which were accurately defined of our conscience, but a kind of partial and temporary one; and for this reason it was abolished afterwards. — HOMILIES CONCERNING THE STATUES 12.9