Genesis 4:1-8 ESV
Now Adam knew Eve his wife, and she conceived and bore Cain, saying, “I have gotten a man with the help of the LORD.” And again, she bore his brother Abel. Now Abel was a keeper of sheep, and Cain a worker of the ground. In the course of time Cain brought to the LORD an offering of the fruit of the ground, and Abel also brought of the firstborn of his flock and of their fat portions. And the LORD had regard for Abel and his offering, but for Cain and his offering he had no regard. So Cain was very angry, and his face fell. The LORD said to Cain, “Why are you angry, and why has your face fallen? If you do well, will you not be accepted? And if you do not do well, sin is crouching at the door. Its desire is contrary to you, but you must rule over it.”
Cain spoke to Abel his brother. And when they were in the field, Cain rose up against his brother Abel and killed him.
ESV: English Standard Version 2016