Charles Ellicott Commentary Leviticus 25:28

"But if he be not able to get it back for himself, then that which he hath sold shall remain in the hand of him that hath bought it until the year of jubilee: and in the jubilee it shall go out, and he shall return unto his possession." — Leviticus 25:28 (ASV)

Not able to restore it to him. —This means, if the seller is unable to return to the buyer the probable value of the crops between the contemplated redemption and the next jubilee year.

Then that which is sold. —In that case, the land thus sold is to continue with the buyer until jubilee, when it is to revert to the seller without any repayment whatsoever. The purpose of this law was to secure for each family a permanent interest in the soil and to prevent the accumulation of land by the greedy few who are always anxious to join field to field, thus preventing the existence of landless beggars and too extensive landed proprietors.

The laws of inheritance (Numbers 27:6–11; Numbers 36:5–13) had a similar purpose. Similar laws existed among other ancient nations. Laws were enacted stating that the lots distributed among the inhabitants could neither be sold nor bought. Solon enacted a law that no one should acquire as much land as he wished, while Plato held that no individual was to possess more than four times the quantity of land held by the lowest owner, who had only a single lot.