c. 390 · John Chrysostom, Homilies on the Gospel of Matthew 17.4
And not thus only, but in another way also He hath lightened the enactment: forasmuch as even for him He leaves one manner of dismissal, when He saith, “Except for the cause of fornication;” since the matter had else come round again to the same issue. For if He had commanded to keep her in the house, though defiling herself with many, He would have made the matter end again in adultery. Seest thou how these sayings agree with what had gone before? For he who looks not with unchaste eyes upon another woman, will not commit whoredom; and not committing whoredom, he will give no occasion to the husband to cast out his wife. Therefore, you see, after this He presses the point without reserve, and builds up this fear as a bulwark, urging on the husband the great danger, if he do cast her out, in that he makes himself accountable for her adultery. Thus, lest thou being told, “pluck out the eye,” shouldest suppose this to be said even of a wife: He added in good time this corrective, in one way only giving leave to cast her out, but no otherwise.