Genesis 4 (NRSVUE):

2b Now Abel was a keeper of sheep, and Cain a tiller of the ground. 3 In the course of time Cain brought to the Lord an offering of the fruit of the ground, 4 and Abel for his part brought of the firstlings of his flock, their fat portions. And the Lord had regard for Abel and his offering, 5 but for Cain and his offering he had no regard. So Cain was very angry, and his countenance fell. 6 The Lord said to Cain, “Why are you angry, and why has your countenance fallen? 7 If you do well, will you not be accepted? And if you do not do well, sin is lurking at the door; its desire is for you, but you must master it.”

8 Cain said to his brother Abel, “Let us go out to the field.”[b] And when they were in the field, Cain rose up against his brother Abel and killed him. 9 Then the Lord said to Cain, “Where is your brother Abel?” He said, “I do not know; am I my brother’s keeper?” 10 And the Lord said, “What have you done? Listen, your brother’s blood is crying out to me from the ground!