Genesis 4:
6 So 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 lies at the door. And its desire is for you, but you should rule over it.”
8 Now Cain talked with Abel his brother;[a] and it came to pass, when they were in the field, that Cain rose up against Abel his brother and killed him.
9 Then the Lord said to Cain, “Where is Abel your brother?”
He said, “I do not know. Am I my brother’s keeper?”