Isaac was apparently a godly man, leading a quiet and uneventful life that was spent within a circle of a few miles, without going through so many adventures and trials as his father. He is mentioned in Genesis as a part of the story of the life of his father Abraham, and in the report on his children.
Heir of God's promise to Abraham, Isaac did not rush into marriage but married when he was forty years old, after his father found him a bride. He later discovered that Rebekah was barren, and after many years he prayed to the LORD about it, and his prayers were answered: she conceived a pair of twins who were born after twenty years of marriage.
But there was no harmony between the twins. Even before birth, they were already fighting one another. Their mother, puzzled because of this, asked the LORD for the reason and He explained that the two would be fathers of two distinct nations, that one would be stronger than the other, and that the older would serve the younger.
They were a type of the constant struggle between good and evil, between light and darkness, between spirit and flesh. As the LORD revealed to the prophet Malachi, He loved Jacob and hated Esau (Malachi 1:2-3), because Esau was profane (Hebrews 12:16). The LORD, omniscient, knew what would happen later.
Esau was born first, and he was red and hairy, so they called his name Esau, meaning “rough”, later earning the title of Edom, “red”, the colour of the earth (the same as Adam). The second was holding him by the leg, so was given the name of Jacob (translated as James in the New Testament) which means “heel catcher”, that is “the supplanter”, he who follows immediately after another. Abraham was still alive, being one hundred and sixty years old at that time.
The twins were not only different physically, but also in character:
Esau grew up to become an expert hunter (like Nimrod - Chapter 10:9), while Jacob was mild (friendly, godly, refined), dwelling in tents.
Esau lived for material pleasures; Jacob strived for the blessing of the LORD.
Esau enjoyed the preference of his father, because Isaac liked eating of the game he hunted. Jacob was the favourite of his mother, being meek and homely.
Their nature was proved in the incident reported here: Jacob, a good cook, had prepared a thick stew of lentils. Esau had just returned from the field, and was tired and hungry: the stew, reddish in colour, was ready to be eaten. Esau then asked Jacob to give him some of this“red” (red stew).
Jacob, seeing an opportunity to make a good deal, proposed that Esau sell him his birthright first; here we see that Jacob resented the fact that Esau was born before him, and wanted to acquire the advantages it brought: to be the head of the family after the father, and the main heir.
Notice that Jacob was not proposing an exchange for a bowl of stew, but a purchase and sale: Jacob valued the birthright highly and would certainly be willing to pay enough for it, if necessary.
But, no doubt to his surprise, Esau declared that he was about to die (a gross exaggeration, for no son of wealthy Isaac would die of hunger), and that the birthright was worthless to him.
Losing no time, Jacob got him to swear and sell him his birthright. That done, Jacob was happy to give him bread and stew of lentils, which Esau ate and drank, rose and went away, so despising his birthright.
R David Jones
19 This is the genealogy of Isaac, Abraham's son. Abraham begot Isaac.
20 Isaac was forty years old when he took Rebekah as wife, the daughter of Bethuel the Syrian of Padan Aram, the sister of Laban the Syrian.
21 Now Isaac pleaded with the LORD for his wife, because she was barren; and the LORD granted his plea, and Rebekah his wife conceived.
22 But the children struggled together within her; and she said, "If all is well, why am I like this?" So she went to inquire of the LORD.
23 And the LORD said to her: "Two nations are in your womb, Two peoples shall be separated from your body; One people shall be stronger than the other, And the older shall serve the younger."
24 So when her days were fulfilled for her to give birth, indeed there were twins in her womb.
25 And the first came out red. He was like a hairy garment all over; so they called his name Esau.
26 Afterward his brother came out, and his hand took hold of Esau's heel; so his name was called Jacob. Isaac was sixty years old when she bore them.
27 So the boys grew. And Esau was a skillful hunter, a man of the field; but Jacob was a mild man, dwelling in tents.
28 And Isaac loved Esau because he ate of his game, but Rebekah loved Jacob.
29 Now Jacob cooked a stew; and Esau came in from the field, and he was weary.
30 And Esau said to Jacob, "Please feed me with that same red stew, for I am weary." Therefore his name was called Edom.
31 But Jacob said, "Sell me your birthright as of this day."
32 And Esau said, "Look, I am about to die; so what is this birthright to me?"
33 Then Jacob said, "Swear to me as of this day." So he swore to him, and sold his birthright to Jacob.
34 And Jacob gave Esau bread and stew of lentils; then he ate and drank, arose, and went his way. Thus Esau despised his birthright.
Genesis chapter 25, verses 19 to 34