John Chrysostom
Lest you think this was said from hostile feeling, he says, I say not only to you, but to every man who is circumcised, that he is obliged to fulfill the whole Law. For the ordinances of the Law are closely bound together. A free man who has given himself into slavery no longer does what he wishes, but submits to all the laws of slavery. So it is also in relation to the Law. If you accept even one small part of it and subject yourself to its yoke, you draw its whole authority upon yourself. The same happens with worldly inheritance. One who takes nothing from it is free from all obligations laid upon the heir of the deceased. But if someone receives even a small part of it, though not the whole inheritance, he assumes all the obligations of the heir for that part.
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The same happens in relation to the Law, and not only in the way I have said, but in another way also. The commandments of the Law are bound together. For example, circumcision is joined to sacrifice and to the observance of days and place. The place is joined to countless kinds of purifications. The purifications are inseparable from many different rites. The unclean man is permitted neither to offer sacrifice, nor to enter the holy places, nor to do anything else of this kind. Thus the Law requires much even for one commandment. If you were circumcised, but not on the eighth day, then your labors have perished. If on the eighth day, but without sacrifice, they have perished. If even with sacrifice, but not in the appointed place, they have perished. If in the appointed place, but not according to the prescriptions of the Law, they have perished. If according to the prescriptions of the Law, but while unclean, they have perished. If clean, but purified by rites not appointed, then all these labors of yours have perished. This is why he says that the one circumcised is obliged to fulfill the whole Law. If the Law has dominion, fulfill not part of it but all of it. If it has no force, do not fulfill even part of it.