1,486. Conditions that Contradict the Torah
Hilchos Ishus 6:10
Pursuant to the parameters in halacha 6:9, if a man consecrates a woman on the condition that he not be obligated to provide her with food, clothes or conjugal rights, his condition is valid as far as food and clothes because these are financial obligations (which can be waived) but it is not valid as far as conjugal rights because it is a (non-financial) Torah obligation. Accordingly, that condition is irrelevant, marriage is effected and he is obligated to grant his wife her conjugal rights. One cannot relieve himself of such an obligation by making a condition. The same is true in all comparable scenarios. Similarly, if a man consecrates a woman he took captive in war on the condition that he can have her perform menial tasks for him, marriage is effected but he may not have her perform these tasks. This is because the Torah does not allow him to do so after having relations with her (see Deuteronomy 21:14). He cannot make a condition that grants him a right that the Torah denies him. Again, this holds true in all similar cases.
Hilchos Ishus 6:11
Let’s say that a man made a condition when marrying or divorcing a woman that she must engage in an incestuous relationship. In such a case, it’s like the previously-discussed impossible condition that she ascend to the heavens or descend to the depths; such a condition is completely immaterial because it’s not up to the woman to make someone else participate in a prohibited relationship. Therefore, this is a condition that she is not capable of fulfilling. The same is true in all comparable situations.