Murder most foul

(7)“Cain said to Abel his brother. It was when they were in the field. Cain rose up against Abel his brother and killed him” (Genesis 4:8).
“Cain said to Abel his brother. It was when they were…” – about what were they quarreling? They said: ‘Let us divide the world between us.’ One took the land and one took the movable property. This one said: ‘The land on which you are standing is mine.’ That one said: ‘What you are wearing is mine.’ That one said: ‘Take it off.’ This one said: ‘Fly.’ As a result: “Cain rose up against Abel his brother and killed him.”
Rabbi Yehoshua of Sikhnin said in the name of Rabbi Levi: Both of them took the land and both of them took the movable property. Regarding what, then, were they quarreling? Rather, this one said: ‘The Temple shall be built in my domain,’ and that one said: ‘The Temple shall be built in my domain,’ as it is stated: “It was when they were in the field,” and “field” is nothing other than the Temple, as it says: “Zion will be plowed like a field” (Micah 3:12). As a result: “Cain rose up against Abel his brother…”
Yehuda bar Rabbi said: They were quarreling over [who would wed] the first Eve. Rabbi Aivu said: The first Eve had returned to dust. Regarding what, then, were they quarreling? Rabbi Huna said: An extra twin sister was born with Abel. This one [Cain] said: ‘I will take her, as I am the firstborn.’ That one [Abel] said: ‘I will take her, as she was born with me.’ As a result: “Cain rose up.”