Bede : And the Lord said to him: Why are you angry, and why has your countenance fallen? If you do well, will you not be accepted? But if you do not do well, sin lies at the door? Why, he says, are you angry, and why are you tortured with envy of your brother, and you cast your eyes down to the ground? If you do well, if you offer your sacrifice with a pure heart, will you not be accepted, with the Lord looking favorably upon you and your sacrifice? But if you do not do well, sin lies at the door, and by having such a doorkeeper, you will always enter and exit with him accompanying you, instead of the Lord guarding your going in and coming out, just as it is said of wisdom: Whoever rises early to seek her will not toil, for he will find her sitting at his doors (Wisdom 6:15). And again: Because she goes about seeking those worthy of her and graciously shows herself to them on their ways, and meets them with all providence (Wisdom 6:17). — Commentary on Genesis (Hexaemeron) Ephrem the Syrian : God said to Cain, "Why are you angry, and why is your face gloomy?" Instead of being filled with anger, you ought to be filled with distress. Instead of your face being gloomy, tears ought to be flowing from your eyes. "If you do well, I will accept it." Notice then that it was not because of the small size of Cain's offering that it was rejected. It was not accepted because of his spitefulness and his lack of good will. "If you do well, I will accept it," even though I did not accept it before, and it will be accepted along with the chosen offering of your brother even though it was not accepted before. "But if you do not do well, sin is couching at the first door." Abel will listen to you through his obedience, for he will go with you to the plain. There you will be ruled over by sin, that is, you shall be completely filled with it. But instead of doing well so that the offering that had been rejected might be credited to Cain as acceptable, he then made an offering of murder to that One to whom he had already made an offering of negligence. — COMMENTARY ON Genesis 3.4.1-3 Jerome : (Verse 6.) And the Lord said to Cain: Why is your face downcast? If you do what is right, will you not be accepted? But if you do not do what is right, sin is crouching at your door; it desires to have you, but you must master it. We are compelled to linger longer on each individual. For even now the meaning is very different in the Hebrew than in the translators of the Septuagint. For the Lord said to Cain: Why are you angry? Why is your face downcast? If you do what is right, will you not be accepted? But if you do not do what is right, sin is crouching at your door; it desires to have you, but you must master it. And to you is his alliance: but you must rule over him more. But, he says: Why are you angry, and why are you tormented by envy towards your brother, with the bitterness of jealousy, you turn your face to the ground? If you do well, will not your sin be forgiven you? Or, as Theodotion says, will it be acceptable: that is, I will accept your offering, as I have accepted your brother's? But if you do evil, then sin will immediately sit before your doorstep, and you will be accompanied by such a guardian. But because you have free will, I advise you to not be conquered by sin, but to conquer sin. The mistake that the Septuagint interpreters made is this: that the word for sin, which is 'Attath' in Hebrew, is masculine gender, but in Greek it is feminine gender. And those who translated it, translated it with the masculine gender (as it was in Hebrew). — Hebrew Questions on Genesis John Chrysostom : God wishes to defuse the wild frenzy and remove the anger by means of his words. You see, he observed the stages of Cain's thinking and realized the savagery of his deadly intention; so he intends at this early stage to sedate his thinking and bring repose to his mind by placing his brother subject to him and not undermining his authority. But even despite such great concern and such potent remedies, Cain gained nothing from the experience. Such was the degree of difference in their attitudes and the excess of evil intent. — HOMILIES ON Genesis 18.24 John Chrysostom : Consider, I ask you, dearly beloved, the ineffable considerateness in his care when he saw Cain under assault, so to speak, from the passion of envy, see how out of fidelity to his own goodness he applied various remedies to him so that he might be quickly plucked from the water and not be drowned. "'For what reason are you annoyed? For what reason has your face fallen?"' Why on earth, he is saying, are you overcome with such resentment as to show the extent of your displeasure on your face? "'For what reason has your face fallen?'" Why has this event so affected you? Why have you not considered what your obligation was? You weren't making your offering to a human being, capable of being deceived, were you. Did you not realize that I wasn't looking for some offering or other of yours, but for the pure intention of the offerer? "'For what reason are you annoyed? For what reason has your face fallen? Is it not true that, even if you make your offering correctly but fail to choose the offering correctly, you commit sin?" That is to say, while your having the idea of making an offering was commendable, still your not choosing the offering correctly led to the rejection of the offering. I he one who makes an offering to God, you know, must show great care in the choice, and the greater the difference between the recipient and the offerer, the greater the distinction you should lend to your choice. You, however, gave no thought to these matters but simply offered whatever came to hand; hence they in turn could not be judged acceptable. You see, just as your intention in making the offering did not make allowance for the difference in status, and so caused the offering presented by you to be rejected; in like manner, your brother's intention, which happened to be correct and revealed great care in the choice, caused his gifts to be acceptable. Still, I am not demanding a penalty for the error but merely highlighting the sin and offering you advice, provided you want to take it, mend your ways and not involve yourself in worse evils.