There it is perhaps guessing at the disparity between the animals. It is at the same time showing clearly that we must not wrong any of those from other races by bringing them under the same yoke when we have nothing against them apart from their foreignness, for which they are not responsible, which is not an immoral trait and does not spring from one. It is my view that this is an allegory, meaning that we should not share the cultivation of the Logos on equal terms between pure and impure, faithful and faithless, as the ox is accounted a clean animal and the donkey unclean.
What does Scripture mean by these riddles? That it is not right for evil and virtue to grow together in the same soul. Nor is it right, dividing one’s life between opposites, to reap thorns and grain from the same soul. Nor is it right for the bride of Christ to commit adultery with the enemies of Christ or to bear light in the womb and beget darkness.
Man is forbidden to plow with an ox and an ass at the same time. This is as if to say you should not bring together fools and the wise to hear your teaching. Otherwise you will cause the one who cannot fulfill your words to stand in the way of the one who can.
[AD 215] Clement of Alexandria on Deuteronomy 22:10