"וַיֹּאמֶר קַיִן אֶל-הֶבֶל אָחִיו ...”

And the man knew Eve his wife; and she conceived and bore Cain, and said: ‘I have agotten a man with the help of the LORD.’ And again she bore his brother Abel. And Abel was a keeper of sheep, but Cain was a tiller of the ground. And in process of time it came to pass, that Cain brought of the fruit of the ground an offering unto the LORD. And Abel, he also brought of the firstlings of his flock and of the fat thereof. And the LORD had respect unto Abel and to his offering; but unto Cain and to his offering He had not respect. And Cain was very wroth, and his countenance fell. And the LORD said unto Cain: ‘Why art thou wroth? and why is thy countenance fallen? If thou doest well, shall it not be lifted up? and if thou doest not well, sin coucheth at the door; and unto thee is its desire, but thou mayest rule over it.’ And Cain spoke unto Abel his brother. And it came to pass, when they were in the field, that Cain rose up against Abel his brother, and slew him. And the LORD said unto Cain: ‘Where is Abel thy brother?’ And he said: ‘I know not; am I my brother’s keeper?’ And He said: ‘What hast thou done? the voice of thy brother’s blood crieth unto Me from the ground. And now cursed art thou from the ground, which hath opened her mouth to receive thy brother’s blood from thy hand. When thou tillest the ground, it shall not henceforth yield unto thee her strength; a fugitive and a wanderer shalt thou be in the earth.’ And Cain said unto the LORD: ‘My punishment is greater than I can bear. Behold, Thou hast driven me out this day from the face of the land; and from Thy face shall I be hid; and I shall be a fugitive and a wanderer in the earth; and it will come to pass, that whosoever findeth me will slay me.’ And the LORD said unto him: ‘Therefore whosoever slayeth Cain, vengeance shall be taken on him sevenfold.’ And the LORD set a sign for Cain, lest any finding him should smite him. And Cain went out from the presence of the LORD, and dwelt in the land of Nod, on the east of Eden.

ויאמר קין אל הבל AND CAIN SPAKE TO ABEL — He began an argument, striving and contending with him, to seek a pretext to kill him. There are Midrashic explanations of these words, but this is the plain sense of the text.

(7) “And Cain spoke to Abel his brother, and it came to pass when they were in the field…” (Genesis 4:8) What were they arguing about? They said: come let’s divide up the world, one will take the land and one will take the moveable property. This one said: the ground you are standing on is mine. The other one said: what you are wearing is mine. This one said: take it off! The other one said: fly! Because of this “…Cain rose against his brother Abel and killed him.” (ibid.) R’ Yehoshua of Sakhnin said in the name of R’ Levi: they both took the land and the moveable property. What were they arguing about? One said: the Holy Temple will be built in my boundary. The other said: the Holy Temple will be built in my boundary. As it says “…when they were in the field…” (ibid.) and the field only refers to the Holy Temple. This is what it says “…Zion shall be plowed as a field…” (Micah 3:12) Because of this “…Cain rose up against Abel his brother and slew him.” Yehudah bar Ami said: they were arguing about the first Eve. R’ Ibo said: the first Eve returned to the dust. Then what were they arguing about? R’ Huna said: an extra twin sister was born with Abel. This one said: I will take her because I am the first born. The other one said: I will take her because she was born with me. Because of this “…Cain rose up against Abel his brother and slew him.”