Genesis 4:11

7 If you do what is right, will you not be accepted? But if you refuse to do what is right, sin is crouching at your door; it desires you, but you must master it.”

8 Then Cain said to his brother Abel, “Let us go out to the field.” And while they were in the field, Cain rose up against his brother Abel and killed him.

9 And the LORD said to Cain, “Where is your brother Abel?” “I do not know!” he answered. “Am I my brother’s keeper?”

10 “What have you done?” replied the LORD. “The voice of your brother’s blood cries out to Me from the ground.

11 Now you are cursed and banished from the ground, which has opened its mouth to receive your brother’s blood from your hand.

12 When you till the ground, it will no longer yield its produce to you. You will be a fugitive and a wanderer on the earth.”

13 But Cain said to the LORD, “My punishment is greater than I can bear.

14 Behold, this day You have driven me from the face of the earth, and from Your face I will be hidden; I will be a fugitive and a wanderer on the earth, and whoever finds me will kill me.”

15 “Not so!” replied the LORD. “If anyone slays Cain, then Cain will be avenged sevenfold.” And the LORD placed a mark on Cain, so that no one who found him would kill him.

Read all of Genesis 4