What was the issue with Cain's offering vs Able's? Able offered the first fruits of his labor while Cain offered what he had left over. It is a heart issue. Cain's response to God's rebuke is to kill his brother. Rather than turning from his sin, he allowed himself to be consumed by his anger. God's reaction seems harsh. But he reality he is extending grace to Cain. Cain is allowed time to repent and return to the Lord.