Bava Metzia 108B

ואי לא, איערומי קא מערים.

But if this field is not of any distinct quality, he is certainly trying to employ an artifice. His plan is to then purchase another plot of land from this owner, one that does border on the field of a neighbor. By first buying the plot in the middle, he is trying to establish himself as a neighbor so that the other neighbors will not have the first right of purchase relative to him. Therefore, the neighbors may prevent him from buying the second plot of land.

מתנה לית בה משום דינא דבר מצרא. אמר אמימר: אי כתב ליה אחריות ⁠– אית בה משום דינא דבר מצרא.

The Talmud continues to discuss the halakha of one whose field borders that of his neighbor. With regard to a gift, it is not subject to the halakha of one whose field borders the field of his neighbor, as one can give a gift to whomever he chooses. Ameimar said: If he wrote a property guarantee to the recipient of the gift that if the field is seized for payment of a debt of the giver the giver of the gift will compensate the recipient for his loss, it is subject to the halakha of one whose field borders of the field of his neighbor. In that case the supposed gift has the appearance of a sale, so the neighbor can force the recipient to sell the plot to him.

מכר כל נכסיו לאחד ⁠– לית בה משום דינא דבר מצרא. לבעלים הראשונים ⁠– לית בה משום דינא דבר מצרא. זבן מגוי וזבין לגוי ⁠– לית בה משום דינא דבר מצרא.

If a seller sold all his property to a single person, this sale is not subject to the halakha of one whose field borders the field of his neighbor, as the seller is not required to leave out one particular field if the buyer is acquiring all his property. Similarly, if the seller sold it back to the previous owners, this sale is not subject to the halakha of one whose field borders the field of his neighbor. If a buyer bought a field from a non-Jew or a seller sold a field to a non-Jew, this purchase or sale is not subject to the halakha of one whose field borders the field of his neighbor.