Genesis 4:5

2 Then again she became with child and gave birth to Abel, his brother. And Abel was a keeper of sheep, but Cain was a farmer.

3 And after a time, Cain gave to the Lord an offering of the fruits of the earth.

4 And Abel gave an offering of the young lambs of his flock and of their fat. And the Lord was pleased with Abel's offering;

5 But in Cain and his offering he had no pleasure. And Cain was angry and his face became sad.

6 And the Lord said to Cain, Why are you angry? and why is your face sad?

7 If you do well, will you not have honour? and if you do wrong, sin is waiting at the door, desiring to have you, but do not let it be your master.

8 And Cain said to his brother, Let us go into the field: and when they were in the field, Cain made an attack on his brother Abel and put him to death.