It is my understanding that Esau was a hunter of game in the field, and travelled into the countryside to find wild game to kill and eat. He also gave Isaac, His father, some of the game that he had killed to eat as well, and Isaac regarded/loved Esau more than he regarded/loved Jacob.
These verses, which I had previously posted above tell us this: -
Genesis 25:27-28: - 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.
The Book of Jasher, chapter 27, gives us an account of Esau selling his birthright to Jacob when he had come into the tent of Jacob.
In this account we are told that Esau had killed Nimrod and taken his clothes of office which his father had given him, the very skins that God had given Adam to cover him.
Now whether or not we accept this version as to why Esau sold his birthright is immaterial, the Bible is silent as to what Esau was doing before he entered Jacob's tent and asked for some of what Jacob was preparing to eat.
Genesis 25:29-34: - Esau Sells His Birthright
(Heb 12:16)
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.
Why did Esau say to Jacob, "
Look, I am about to die; so what is this birthright to me?" The passage is silent as to why Esau would think that he was about to die.
The passage is also silent as to what it meant when it states, "Now Jacob cooked a stew; and
Esau came in from the field, and he was weary."
The Bible is silent as to the age of the twin brothers in this passage and also as to what it means when it tells us that Esau had come in from the field. You have placed your interpretation on the passage as to what Esau had been doing and where he had been before entering Jacob tent and asking for some food.
The problem is the interpretation and subsequent understanding that you have placed on the above passage.
The information in Chapter 27 of the Book of Jasher, does not, as you claim, contradict the above passage, but it does call into question your interpretation and understanding from the silence of the passage with regards to what the background story might have been.
The passage from the Book of Jasher suggests that Esau tried to take, by force, God's purposes for his life whereas, Jacob quietly was waiting for God's Blessing to be given to him.
Shalom