Genesis 4:9

And the LORD said unto Cain, Where [is] Abel thy brother? And he said, I know not: [Am] I my brother's keeper?

Genesis 4:8

And Cain talked with Abel his brother: ["saying, let us go out into the field] and it came to pass, when they were in the field, that Cain rose up against Abel his brother, and slew him.

Genesis 4:4

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:

Genesis 4:2

And she again bare his brother Abel [lit breath, or nothing]. And Abel was a keeper of sheep, but Cain was a tiller of the ground.