Genesis 4:6

3 And in process of time it came to pass, that Cain brought of the fruit of the ground an offering unto Jehovah.

4 And Abel, he also brought of the firstlings of his flock and of the fat thereof. And Jehovah had respect unto Abel and to his offering:

5 but unto Cain and to his offering he had not respect. And Cain was very wroth, and his countenance fell.

6 And Jehovah said unto Cain, Why art thou wroth? and why is thy countenance fallen?

7 If thou doest well, shall it not be lifted up? and if thou doest not well, sin coucheth at the door: and unto thee shall be its desire, but do thou rule over it.

8 And Cain told 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.

9 And Jehovah said unto Cain, Where is Abel thy brother? And he said, I know not: am I my brother`s keeper?