Genesis 4:8-10
Now Cain said to his brother Abel, "Let's go out to the field." And while they were in the field, Cain attacked his brother Abel and killed him.
Then the LORD said to Cain, "Where is your brother Abel?" "I don't know," he replied. "Am I my brother's keeper?"
The LORD said, "What have you done? Listen! Your brother's blood cries out to me from the ground.