Genesis 25:31

The right of the oldest son was very important. There were two reasons for this. The oldest son took most of his father’s possessions when his father died. That was one reason, but the other reason was more important. When the father died, the oldest son became the head of the family. But sometimes God chose another son instead of the oldest son. Here are some examples.

• When Abraham died, Isaac had the right of the oldest son. But Ishmael was older than Isaac. (See Genesis 21:12 and the comment.) However, Ishmael’s mother was Hagar, who was Abraham’s extra wife. So Ishmael was not a son of Abraham’s wife, Sarah.

• Jacob took Esau’s right of the oldest son. (See verse 33.) God made this happen.

• Manasseh was Joseph’s oldest son. But God told Jacob to bless Ephraim as if he was the oldest. (See Genesis 48:5; Genesis 48:13; Genesis 48:19.) Jacob was Joseph’s father and he was the grandfather of Ephraim and Manasseh.

• Reuben was Jacob’s oldest son. But God told Jacob to bless Judah as the oldest son instead of Reuben. (See Genesis 49:4; Genesis 49:8.) Judah was Jacob’s third son.

So God chooses the best person to do his work. That is not always the oldest person.

v33 Jacob said, ‘Make a firm promise to me before you eat.’ So Esau made a firm promise to Jacob. He sold to Jacob the right of the oldest son. v34 Then Jacob gave to Esau bread and meat and vegetables. Esau ate and drank. Then he stood up and he went away. So he did not think that the right of the oldest son was important.