37 And Isaac answered and said unto Esau, Behold, I have made him thy lord, and all his brethren have I given to him for servants; and with corn and wine have I sustained him: and what shall I do now unto thee, my son? 38 And Esau said unto his father, Hast thou but one blessing, my father? bless me, even me also, O my father. And Esau lifted up his voice, and wept. 39 And Isaac his father answered and said unto him, Behold, thy dwelling shall be the fatness of the earth, and of the dew of heaven from above; 40 And by thy sword shalt thou live, and shalt serve thy brother; and it shall come to pass when thou shalt have the dominion, that thou shalt break his yoke from off thy neck.
Esau continued to plead for some sort of blessing from his father, even after hearing that Jacob had already been promised to rule over his brother’s posterity. And this prophecy would come true after the Israelite Exodus. Jacob’s descendants would enter wars with all the other nations in the promised land, including the Edomites, who were the descendants of Esau. This struggle between the brothers’ posterity would be resolved when Saul and David finally conquered the Edomites, subjugating the nation for many years to come.
However, God did have a small reprieve for Esau, and through Isaac he pronounced that the Edomites would eventually regain their freedom. This would occur in the days of Elisha and Joram, when the Edomites successfully revolted and crowned their own king. They would never go so far as to gain power over the Israelites, but at least they would be their own masters.
But it would be wrong to assume that the Israelites would prevail over the Edomites because of this one time where Jacob was more faithful than Esau. The Israelites prevailed in the time of David because they were more worthy at that time. And the Edomites eventually threw off the Israelites because the Israelites were no longer more worthy at that time. Sometimes we make the mistake of thinking that when God foretells good or bad for a nation, it is a recompense for a decision made by a single ancestor. This was a misconception that Jesus had to correct his own disciples on many years later. When God foretold that Jacob’s descendants would rule over Esau’s he was merely foretelling that their descendants would earn that outcome for themselves.