Rashi: Normally, one who sells his field mourns. He will not, for you are destined to be exiled. Malbim - the buyer will not rejoice that he became rich.

Radak: Normally, the buyer rejoices and the seller mourns, for he sold due to [financial] pressure. Also Chachamim said, people say, if you bought, you gained; if you sold, you lost' (Bava Metzi'a 51a). The Navi teaches that one who sells his field in Eretz Yisrael, he should not mourn over this, for even if he would not sell it, he would keep it only a short time. Soon he will be exiled and leave. Also the buyer should not rejoice, for he will keep it only a short time.

Radak: Yes - anger will come from Me to kill them and exile them.

Malbim: This is why this time came, for there is anger over their sins.