Genesis 4:3-5, 15, 25

And in the process of time it came to pass that Cain brought an offering of the fruit of the ground to the LORD. Abel also brought of the firstborn of his flock and of their fat. And the LORD respected Abel and his offering, but He did not respect Cain and his offering. And Cain was very angry, and his countenance fell.

And the LORD said to him, “Therefore, whoever kills Cain, vengeance shall be taken on him sevenfold.” And the LORD set a mark on Cain, lest anyone finding him should kill him.

And Adam knew his wife again, and she bore a son and named him Seth, “For God has appointed another seed for me instead of Abel, whom Cain killed.”