Sin Crouching at the Door: Genesis 4:7
Sin is personified by God as a beast crouching at the door, seeking, presumably, to overpower Cain. Just as Adam was tasked with ruling over the beasts of the field, so Cain must rule over sin. In the very next verse it is Cain who rose up against his brother, himself acting with animalistic violence.
“Blessed is the one … whose delight is in the law of the Lord, and who meditates on his law day and night. That person is like a tree planted by streams of water that yields its fruit in season.”
— Psalm 1:1-3