What does the Bible say about the sacrifice of Cain and Abel?

In Genesis 4, Abel's offering was respected by God because it was a blood sacrifice, pointing to the necessity of the shedding of blood for the remission of sins. In contrast, Cain's offering, which was based on his own works from the ground, was not accepted. This illustrates God's established way of salvation through sacrifice, namely through Christ, who is the ultimate lamb without spot or blemish. Abel represents the way of faith and dependence on God's grace, while Cain represents self-righteousness and attempts to earn favor through works.