Mass. Gen. Laws ch. 184, § 2: Conveyance of land subject to contingent remainder, executory devise or other estate in expectancy

Section 2. If a contingent remainder, executory devise or other estate in expectancy is so granted or limited to a person that in case of his death before the happening of the contingency the estate would descend to his heirs in fee simple, he may, before the happening of the contingency, sell, assign or devise the land subject to the contingency.