על החוקים לפרטיהם, ספר ג ה׳On the Special Laws, Book III 5
א׳
1[26] On this principle he prohibits many other unions, not allowing marriage with a son’s daughter or a daughter’s daughter, nor with an aunt whether paternal or maternal, nor with one who has been wife to an uncle or son or brother, nor again with a stepdaughter whether widow or unmarried, I need not say while the wife is alive, heaven forbid, but even after her death. For the stepfather is virtually a father whose duty is to set his wife’s daughter in the same position as his own.
ב׳
2[27] Again, he does not allow the same man to marry two sisters either at the same or at different times, even if the person in question has repudiated the one he married first. For while she is still alive either as his consort or divorced, whether she is remaining in widowhood or has married another, he considered that the law of holiness required that the sister should not take the position which the wife has lost by her misfortune, but should learn not to set at nought the rights of kinship, nor use as a stepping-stone the fallen state of one so closely united to her by birth, nor bask at ease while enjoying and returning the caresses of her sister’s enemies.
ג׳
3[28] For from this source grow grave jealousies and bitter feuds bringing with them train upon train of evils without number. For it is just as if the parts of the body were to renounce their natural partnership and place in the system and engage in strife with each other, thus producing incurable diseases and fatalities. Sisters though made as separate parts of the system are fitted into it and formed into a single whole by nature and identity of parentage. And jealousy is a most troublesome passion, creating if it breaks out grave evils unknown before and hardly to be cured.
ד׳
4[29] But also, he says, do not enter into the partnership of marriage with a member of a foreign nation, lest some day conquered by the forces of opposing customs you surrender and stray unawares from the path that leads to piety and turn aside into a pathless wild. And though perhaps you yourself will hold your ground steadied from your earliest years by the admirable instructions instilled into you by your parents, with the holy laws always as their key-note, there is much to be feared for your sons and daughters. It may well be that they, enticed by spurious customs which they prefer to the genuine, are likely to unlearn the honour due to the one God, and that is the first and the last stage of supreme misery.
ה׳
5[30] Another commandment is that if a woman after parting from her husband for any cause whatever marries another and then again becomes a widow, whether this second husband is alive or dead, she must not return to her first husband but ally herself with any other rather than him, because she has broken with the rules that bound her in the past and cast them into oblivion when she chose new love-ties in preference to the old.
ו׳
6[31] And if a man is willing to contract himself with such a woman, he must be saddled with a character for degeneracy and loss of manhood. He has eliminated from his soul the hatred of evil, that emotion by which our life is so well served and the affairs of houses and cities are conducted as they should be, and has lightly taken upon him the stamp of two heinous crimes, adultery and pandering. For such subsequent reconciliations are proofs of both. The proper punishment for him is death and for the woman also.