Ketubot 94A

כגון שנמצאת אחת מהן שדה שאינה שלו. ובבעל חוב מאוחר שקדם וגבה קמיפלגי.

The case is where it is discovered that one of the fields in the estate is not his field, e.g., the husband had stolen it from someone else. Consequently, it is likely that the field will be repossessed, and if it is used to pay the marriage contract of one of the first 3 wives, that wife stands to lose out. And they disagree with regard to a creditor whose promissory note was dated later than that of another creditor, and yet he collected his debt before the other creditor, leaving nothing for the other creditor to collect. This is parallel to the case of the wives if the 4th wife collects her marriage contract and then one of the earlier wives loses the field she has been paid.

תנא קמא סבר: מה שגבה לא גבה.

The first tanna holds that what the creditor has collected, he has not fully collected, i.e., he will have to give up the property he collected so that the creditor with the earlier promissory note can collect his debt. Similarly, if the property given to one of the first 3 wives is repossessed and there is nothing left for her to collect, the 4th wife will have to relinquish the property that she had been paid to accommodate the wife who preceded her.

ובן ננס סבר: מה שגבה גבה.

And ben Nanas holds that what the creditor has collected, he has collected, i.e., it is not taken from him in order to pay the earlier creditor. Consequently, according to the first tanna, there is no need for the 4th wife to take an oath before she collects the property, because whatever she collects can be taken from her in order to pay the other wives. According to ben Nanas, since the property the 4th wife collects cannot be taken from her, she must take an oath that she is collecting this property legally in order to ensure that none of the other wives will lose out because of what she collects.