Kiddushin, Chapter 3, Mishnah 3. This mishnah is essentially similar to the previous one, and it deals with a man who betroths a woman on condition that he owns a field.
"Al menas she'yesh li beis kor afar":
The man betrothing the woman tells her that he is betrothing her on condition that he owns a beis kor of land. "Afar" means earth in its plain sense, but the intent is a field the size of a beis kor - the area in which thirty se'ah can be sown, which is seventy five thousand square amos.
"Harei zo mekudeshes, vehu she'yesh lo" - the woman is betrothed, provided that he really does own a field of that size.
As we mentioned in the previous mishnah, when it is not known whether he owns such a field or not, we do not say that she is not betrothed at all; rather, she is betrothed out of doubt, since it is possible that he does indeed own such a field.
At first glance there would seem to be room to distinguish between the cases: the previous mishnah dealt with money, and money can be tucked away and concealed. It is possible that he really does have it and is hiding it for some reason - in order to torment her and keep her bound to him while he marries another woman, which is forbidden. But land and a field would seem to be different, and if we know of no such field, we should not assume that he owns one.
Nevertheless, the law is the same in both cases: whether with money or with land and a field, as long as there are no witnesses to the matter, she is betrothed out of doubt.
"Al menas she'yesh li beis kor afar bemakom peloni":
Here the man betrothing her specified a particular location. If he owns such a field in that location - she is betrothed; and if he does not own such a field there - she is not betrothed.
"Al menas she'ar'ech beis kor afar":
With this wording it is not enough that there are witnesses to the existence of the field; rather, the condition is that he actually show it to her: "Harei zo mekudeshes, veyar'enah" - she is betrothed, provided that he shows her the field.
Even so, the field must be his own: "Ve'im her'ah bebik'ah - einah mekudeshes". If he showed her a field in the valley that is not his - for example, he is a sharecropper in that field, or he purchased only the produce of that area - she is not betrothed, since the field does not belong to him.
In summary: in this mishnah we learned the law of one who betroths on condition that he owns a beis kor of land: if he owns one - she is betrothed, and when the matter is unknown - she is betrothed out of doubt, and there is no difference in this between money and land. If he specified a particular location - everything depends on the existence of the field in that location. If he stipulated that he would show her the field - testimony is not enough, he must actually show it to her, and provided that the field is his own and not a field that does not belong to him.