Kiddushin, Chapter Three, Mishnah Two
This mishnah deals with a man who attempts to betroth a woman on condition that he either give her two hundred zuz, has two hundred zuz or owns two hundred zuz.
1) If one says to a woman. Behold, you are betrothed to me on condition that I give you two hundred zuz, she is betrothed, and he must give it.
2) On condition that I give you [two hundred zuz] within thirty days from now: if he gives her within thirty days, she is betrothed; if not, she is not betrothed.
3) On condition that I have two hundred zuz, she is betrothed, providing he has [two hundred zuz].
4) On condition that I show you two hundred zuz, she is betrothed, and he must show her.
a) But if he shows her [money lying] on the table, she is not betrothed.
Section one: In such a case the woman is immediately betrothed and the man must thereafter give her two hundred zuz. If he does not give her two hundred zuz, the betrothal becomes invalid. The problem is that since he didnt set a time limit he has an unlimited time to give her the two hundred zuz. Potentially, the only way for the betrothal to become invalid would be for him to die before he gives her the money. In such a case she would not be considered his widow and she would not be liable for yibbum. Therefore, this is not a particularly good way of performing betrothal, especially for the woman.
Section two: In this case he did set a time limit for the fulfillment of his condition. Therefore, if he doesnt give her the betrothal within thirty days, she is not betrothed. In fact, this may have been a common form of betrothal. The man would have thirty days (or a longer period of time) to come up with the money necessary to betroth the woman and if he did not, the betrothal was invalidated with no need for a get. This prevented the woman from being left hanging.
Section three: In this case, all the man has to do is demonstrate that he owns two hundred zuz. Again, she is betrothed immediately and he must prove that he has two hundred zuz. However, we should note that in order to be certain that the betrothal is invalid she would have to prove that he doesnt own two hundred zuz. This will not be easy and again the woman is in a disadvantageous situation.
Section four: Here he must not only own two hundred zuz, but show her the cash (or its equivalent). He may not show her two hundred zuz lying on a table unless he actually owns them. Just as in section two, this too seems to be better for the woman. Here she can actually see that he owns the two hundred zuz and need not worry about proving (or disproving) it.