Genesis 4:7

If thou doest well, shalt thou not be accepted? And if thou doest not well, sin lieth at the door. The fault lay altogether with Cain himself; for if he had done well, if he had had faith and shown this faith in truly good works, in acceptable offerings, then he would have experienced the appreciation for which he seemed anxious, and could have lifted his countenance in token of a good conscience. If, on the other hand, his sacrifice was not brought in true faith and he was now angry over his rejection, then sin, like a wild, predatory beast, would crouch at the door of his heart, eager for even the slightest opportunity to enter and to work its will. And unto thee shall be his desire, and thou shalt rule over him. That is as it should be in the heart of the child of God. Although the desire of sin is always directed against man with the intention of gaining control over him, yet the believer will keep the upper hand, will hold the wrath of the heart back with the firmness of the sanctified mind.