1,488. When a Conditional Marriage is Effected
Hilchos Ishus 6:14
Some of the later Geonim were of the opinion that only conditions involving marriage and divorce need to include both the positive and negative ramifications but that this is unnecessary in financial matters. It would not be appropriate to rely on this position because the Sages inferred the need to make twofold conditions – as well as the other rules – from the condition made by the Tribes of Gad and Reuven in Numbers 32:29-30: “If the people of Gad... cross over; but if they do not cross over...” – a condition that involved neither marriage nor divorce. It would be appropriate to follow the ruling of the earlier Geonim, with whose position the Rambam agrees.
Hilchos Ishus 6:15
If a man consecrates a woman conditionally, marriage is effected when the condition is fulfilled, not as of the time when he gave her kiddushin. Let’s say that a man tells a woman, “If I give you 200 zuz this year, you are consecrated to me through this dinar, but if I do not give it to you, then you are not consecrated.” If he gave her the kiddushin in Nisan and the 200 zuz in Elul, then marriage is effected in Elul. Therefore, if another man were to consecrate her before the first man fulfills his condition, she is married to the second man. The same rule applies to divorce and financial transactions: divorce, or the transfer of a sale or a gift, is effected when the condition is fulfilled.