Genesis 4:6 - The Popular Commentary by Paul E. Kretzmann

And the Lord said unto Cain, Why art thou wroth, and why is thy countenance fallen? The Lord's warning at this time had reference both to the cause and to the possible consequences of Cain's wrath. He implies, first of all, that the brooding posture assumed by Cain, was unreasonable, foolish, in the circumstances.