Sotah, Chapter Five, Mishnah One
This mishnah teaches that just as the waters check the innocence of the woman, so too they check the guilt or innocence of the man with whom she is suspected of committing adultery. The second part of the mishnah teaches that in cases in which she is prohibited to her husband, she is also prohibited to her suspected lover.
1) Just as the water checks her so the water checks him, as it is said, And shall enter, And shall enter (Numbers 5:22, 27).
2) Just as she is prohibited to the husband so is she prohibited to the lover, as it is said, defiled . . . and is defiled (Numbers 5:27, 29), the words of Rabbi Akiba.
a) Rabbi Joshua said: thus Zechariah ben Hakatzav used to expound.
b) Rabbi says: twice in the portion, If she is defiled defiled–one referring [to her being prohibited] to the husband and the other to the paramour.
Section one: The first four chapters have all been dealing with the woman as suspected adulteress. Now the Mishnah states that the water doesnt only check the woman, but checks the man with whom she is suspected of committing adultery as well, for he is just as guilty as she. If the waters cause her belly to swell and her thigh to fall, then they will do so to him as well.
There are two possible ways of understanding how this midrash works. The first is that the midrash is based on the double appearance of the word and shall enter. The second is that the midrash is based on the extra and (the letter vav) in one of the words.
Section two: The mishnah now moves from the midrashic idea that the waters check the suspected adulterer, just as they check the suspected adulteress, to a more normative halakhic statement. In many cases which were discussed above, the mishnah ruled that the woman is forbidden to return to her husband. This would include all cases where, for whatever reason, she doesnt end up drinking the water. Our mishnah teaches that if she is prohibited to her husband, she is likewise prohibited to the suspected adulterer. She may not be divorced and then marry her lover, for in that way she and he would benefit from the adultery. Adultery, according to Jewish law, can never lead to marriage.
Rabbi Akiva learns this ruling from the extra and in the second appearance of the word defiled. Rabbi Joshua says that Zechariah ben Hakatzav also used to expound the extra and in this manner. Rabbi [Judah Hanasi] suggests a different midrashic means by which to get the same result, and that is the repetition of the phrase if she is defiled. There is a dispute among these rabbis how to derive this law from the Torah. There is no dispute, however, about the law itself.