Deuteronomy 28:51
And he shall eat the fruit of thy cattle, and the fruit of thy land, until thou be destroyed: which also shall not leave thee either corn, wine, or oil, or the increase of thy kine, or flocks of thy sheep, until he have destroyed thee.
The verse warns that an enemy nation will eat the fruit of cattle and the fruit of land until the people are destroyed, leaving no corn, wine, or oil, nor increase of kine nor flocks of sheep, so that they are left without food and other provisions. It belongs to the curses Moses read to Israel announcing what disobedience would bring, set in the same chapter in contrast with the blessings that follow obedience. It belongs also to the directions in chapters 26, 27 and 28 that plainly state the blessings of obedience.
It is part of the instruction proving that God's promises are upon condition of obedience, which explains why the adults of the army that left Egypt were refused entrance into the promised land. Read together with chapter 1, the chapter shows the same conditional character of God's promises and explains the same refusal of that adult army to enter the promised land. It illustrates that God sent Israel prosperity or adversity according to obedience to or transgression of the law given at Sinai and kept in the ark, while the ark itself was not a god or a guarantee of success.
The chapter presents God's covenant of mercy that if Israel would diligently hearken to His voice and do right in His sight and give ear to His commandments and keep all His statutes, He would put none of the Egyptian diseases upon them because He heals them. Transgressing the law breaks down the protective barriers He in providence erected to preserve them from disease that they might live in health and holiness and learn obedience, so that disease of every kind comes because of sin. Christ enshrouded in the pillar of cloud journeyed with Israel under His special direction to preserve under His sheltering wing all who would do His will, and the waters of Marah were an object lesson of His power to cure the evils of the human heart.
The curse of disobedience reaches beyond the people to beasts, trees and vegetation, and that curse on people, animals and plant life has grown heavier through continued disobedience, while blessing remains promised on condition of obedience. Foretold by Moses centuries beforehand, the verse was fulfilled in the utter wasting of the land and the severe suffering of Jerusalem during its siege by the Roman armies under Titus. The directions express the principles of the law of God's kingdom made specific so minds are not left in ignorance and uncertainty, imposing a never-ceasing obligation on all blessed with life, health and temporal and spiritual advantages to return gifts, offerings and tithe for sustaining faithful messengers. The message has not grown weak with age but remains as binding and fresh as God's continual gifts, and was repeated by Christ Himself calling followers to consecration and self-denial.