New Defender's Study Bible Notes
4:5 his countenance fell. Cain’s anger reflects pride in his own works which, because of that very fact, God regarded as “evil” (I John 3:12).
4:6 Why art thou wroth. God’s questions reminded Cain that he knew the type of sacrifice required and had no reason to be surprised when God would not accept another.
4:7 rule over him. Note the similar terminology to that of Genesis 3:16b. Just as Eve’s desire would be toward Adam and he would lead her, so would an unrepentant Cain become so committed to rebellion that “Sin” (personified as a crouching animal) would become Cain’s obedient servant.