Genesis 4:5-7 reads “But unto Cain and to his offering he had not respect. And Cain was very wroth (furious), and his countenance fell. And the LORD said unto Cain, Why art thou wroth? and why is thy countenance fallen? If thou doest well, shall thou not be accepted? and if thou doest not well, sin lieth at the door. And unto thee [shall be] his desire, and thou rule over him.

From this account, we learn that the offering of Cain was one that God did not respect because Cain was letting sin rule over him. This makes Cain furious and he has a long (fallen) face which God notices. God also gives him a reason that it is because he did not do well in not being subject to sin that his offering was not accepted. God then gives Cain an opportunity to not let sin rule over him by advising him to do well.

Points to ponder:
God notices our faces and gives us an opportunity to do well and not allow sin to rule over us. But if we continue to let sin rule over us, we can expect the offering of our life (Romans 12:1-2) to be rejected and the outcome is going to be furious and fallen faces of ours. If God’s sees you today, would he see you as one with a furious and fallen face (meaning we are still slaves to sin) or as one whose face is lightened (by the Light of the World), radiant (radiating his glorious Light) and not ashamed (meaning we are slaves of God and not of sin). How is your face?

Genesis 3:5-7 (KJV)
But unto Cain and to his offering he had not respect. And Cain was very wroth, and his countenance fell.
And the Lord said unto Cain, Why art thou wroth? and why is thy countenance fallen?
If thou doest well, shalt thou not be accepted? and if thou doest not well, sin lieth at the door. And unto thee shall be his desire, and thou shalt rule over him.

Psalm 34:5 (KJV)
They looked unto him, and were lightened: and their faces were not ashamed.