Genesis 4:5

(60) Why Cain after some days offers up the first-fruits of his fruits, but when it is said that "Abel offered up first-fruits of the first-born of his flock and of the fat," "after some days" is not added? (#Ge 4:3-4). Moses here intimates the difference between a lover of himself, and one who is thoroughly devoted to God; for the one took to himself the first-fruits of his fruits, and very impiously looked upon God as worthy only of the secondary and inferior offerings; for the expression, "after some days," implies that he did not do so immediately; and when it is said that he offered of the fruits, that intimates that he did not offer of the best fruits which he had, and herein displays his iniquity. But the other, without any delay, offered up the first-born and eldest of all his flocks, in order that in this the Father might not be treated unworthily.

(61) Why, when he had begun with Cain, he still mentions him here in the second place, when he says: "And God had respect unto Abel and unto his offerings; but unto Cain and unto his sacrifices he paid no attention?" (#Ge 4:5). In the first place, because the good man, who is by nature first, is not at first perceived by the outward senses of any man except in his own turn, and by people of virtuous conduct. Secondly, because the good and the wicked man are two distinct characters; he accepts the good man, seeing that he is a lover of what is good, and an eager student of virtue; but he rejects and regards with aversion the wicked man, presuming that he will be prone to that side by the order of nature. Therefore he says here with exceeding fitness, that God had regard, not to the offerings, but to those who offered them, rather than to the gifts themselves; for men have regard to and regulate their approbation by the abundance and richness of offerings, but God looks at the sincerity of the soul, having no regard to ambition or illusion of any kind.

Every kind of honour and happiness was bestowed upon you, and then was fulfilled that which is written, "My beloved ate and drank, and was enlarged and became fat, and kicked." [Deuteronomy 32:15] Hence flowed emulation and envy, strife and sedition, persecution and disorder, war and captivity. So the worthless rose up against the honoured, those of no reputation against such as were renowned, the foolish against the wise, the young against those advanced in years. For this reason righteousness and peace are now far departed from you, inasmuch as every one abandons the fear of God, and has become blind in His faith, neither walks in the ordinances of His appointment, nor acts a part becoming a Christian, but walks after his own wicked lusts, resuming the practice of an unrighteous and ungodly envy, by which death itself entered into the world. [Wisdom 2:24]

For thus it is written: "And it came to pass after certain days, that Cain brought of the fruits of the earth a sacrifice unto God; and Abel also brought of the firstlings of his sheep, and of the fat thereof. And God had respect to Abel and to his offerings, but Cain and his sacrifices He did not regard. And Cain was deeply grieved, and his countenance fell. And God said to Cain, Why are you grieved, and why is your countenance fallen? If you offer rightly, but do not divide rightly, have you not sinned? Be at peace: your offering returns to yourself, and you shall again possess it. And Cain said to Abel his brother, Let us go into the field. And it came to pass, while they were in the field, that Cain rose up against Abel his brother, and slew him." [Genesis 4:3-8] You see, brethren, how envy and jealousy led to the murder of a brother. Through envy, also, our father Jacob fled from the face of Esau his brother [Genesis 27:41-45]. Envy made Joseph be persecuted unto death, and to come into bondage. [Genesis 37:18-28] Envy compelled Moses to flee from the face of Pharaoh king of Egypt, when he heard these words from his fellow-countryman, "Who made you a judge or a ruler over us? Will you kill me, as you killed the Egyptian yesterday?" [Exodus 2:14] On account of envy, Aaron and Miriam had to make their abode without the camp. [Numbers 12:14-15] Envy brought down Dathan and Abiram alive to Hades, through the sedition which they excited against God's servant Moses. [Numbers 16:33] Through envy, David not only underwent the hatred of foreigners, but was also persecuted by Saul king of Israel. [1 Samuel 21:10-15]

In the case of Cain his wickedness did not begin when he killed his brother. For even before that God, who knows the heart, had no regard for Cain and his sacrifice. But his baseness was made evident when he killed Abel.

Abel was very discerning in his choice of offerings, whereas Cain showed no such discernment. Abel selected and offered the choicest of his firstborn and of his fat ones, while Cain either offered young grains or certain fruits that are found at the same time as the young grains. Even if his offering had been smaller than that of his brother, it would have been as acceptable as the offering of his brother, had he not brought it with such carelessness. They made their offerings alternately; one offered a lamb of his flock, the other the fruits of the earth. But because Cain had taken such little regard for the first offering that he offered, God refused to accept it in order to teach Cain how he was to make an offering.

Cain was angry because the offering of his brother had been accepted. Cain became angry on account of the fire that had come down and distinguished between the offerings. His face became gloomy because there was laughter in the eyes of his parents and his sisters when his offering was rejected. They had seen that Cain’s offering had been placed in the midst of the fire and yet the fire did not touch it.

There were two reasons for his annoyance: not just that he alone had been rejected but also that his brother’s gift had been accepted.

Since Abel made his offering with a proper attitude and pure intention, "God took notice," the text saysÐthat is, he accepted, he was satisfied, he approved of them; but it called the offerings gifts, by this means dignifying the attitude of the offerer. "And whereas to Cain and his offerings he paid no heed." Notice the precision of Sacred Scripture: by the phrase "he paid no heed" it shows us the rejection of what was offered, and by calling what was offered from the soil offerings he teaches us something else again. I mean, see how he shows us through the very events and terms that the Lord wants all these things to be done by us so that the kind of intention we have should be made clear through the actions we take, and so that we may be in a position to know that we are subject to a Lord and Creator who brought us from nothing to being. In other words, in naming the sheep gifts and calling the things from the earth offerings, Sacred Scripture teaches us that neither the herding of sheep nor the collection of fruits of the earth is what is looked for by the Lord but simply the disposition of one's attitude. Hence in this case, too, one man proved acceptable with his gift on this score, whereas the other was rejected along with his gift on that account. The verse, "God took notice of Abel and his gifts, whereas to Cain and his offering he paid no heed," let us take in a sense befitting God. I mean, the intention in the words is that he communicated to them the awareness that while he was satisfied with one man's choice, he took umbrage at the other's attitude.
Such, however, is the way God does things; let us now see what follows. "This annoyed Cain very much and his face fell." What is the meaning of the words, "This annoyed Cain very much"? There were two reasons for his annoyance, not just that he alone had been rejected, but also that his brother's gift had been accepted. "This annoyed Cain," the text says, "and his face fell." What was it that annoyed him? Both things annoyed him, the Lord's ignoring his offering and his brother's gift being welcomed. So it was necessary that he recognize his guilt and adjust the error of his ways. After all, our Lord is loving, and when we err he does not turn away from us because of our error as if we continued in the error on the contrary, he keeps no record of it. In order that you may learn this with precision and see the indescribable magnitude of the loving kindness, consider in these present events the exceeding degree of his goodness and the extent of his longsuffering. I mean, when he saw Cain annoyed unreasonably and, so to say, at the point of drowning in the waves of his annoyance, he did not ignore him; instead, that love which he had shown for his father in giving him the opportunity for excuse and opening the way to renewed confidence in the words, "Where are you?" despite that damaging fall the very same love he now demonstrates towards the man who had proved so ungrateful, and stretches out his hand to this person who was at the point of tumbling down the cliff, as you might say, desirous as he was of offering him the opportunity to adjust the error of his ways. So he says to him,

And Cain was very angry, and his countenance fell. How did Cain know that the Lord had looked favorably upon Abel and his offerings, but had turned away his face from himself and his offerings, unless, as some have interpreted, the Lord had set fire to Abel and his sacrifice, but had not set fire to Cain and his sacrifice, that is, by sending fire from the heavens, He accepted Abel's offering, as we often read that this happened to holy men who offered. Cain, on the other hand, had to consume his own sacrifice by fire. For this is what the Apostle seems to mean when he says: By faith Abel offered a more acceptable sacrifice than Cain to God, through which he obtained the testimony that he was righteous, with God bearing witness to his gifts (Hebrews 11:4). Therefore, God testified to Abel's offerings by fire, by accepting them from the heavens, through which we are also taught by the Apostle's testimony that Abel's offering was made acceptable to God by his faith's devotion, and on the contrary, we must understand that Cain was rejected because he did not serve his Creator with complete faith.