8 Now Cain talked with Abel his [f]brother; and it came to pass, when they were in the field, that Cain rose up against Abel his brother and killed him.
9 Then the Lord said to Cain, “Where is Abel your brother?” He said, “I do not know. Am I my brother’s keeper?”
10 And He said, “What have you done? The voice of your brother’s blood cries out to Me from the ground.
11 So now you are cursed from the earth, which has opened its mouth to receive your brother’s blood from your hand.
12 When you till the ground, it shall no longer yield its strength to you. A fugitive and a vagabond you shall be on the earth.”
13 And Cain said to the Lord, “My punishment is greater than I can bear!
14 Surely You have driven me out this day from the face of the ground; I shall be hidden from Your face; I shall be a fugitive and a vagabond on the earth, and it will happen that anyone who finds me will kill me.”
15 And the Lord said to him, “Therefore, whoever kills Cain, vengeance shall be taken on him sevenfold.” And the Lord set a mark on Cain, lest anyone finding him should kill him.
The anger in Cain’s heart does not immediately vent itself in murder, but rather—and in much more realistic fashion—move incrementally from the stage of inner enmity to verbal dispute. This is implied by the initial reference in this verse to Cain “speaking” with Abel. … The verb [should be translated] in the rarer sense of “disputed,” as the same verb is also used in Esther 1:18. In any event, the progressive escalation of inner enmity/anger, to verbal abuse/dispute, and finally—if not addressed—the act of murder, is likewise the patter supplied by Christ in Matthew 5:21-22, for which the present passage is almost certainly in view (cf. v.22: “everyone who is angry with his brother”). — Wechsler, pages 118-119.
The seed of the Serpent was quickly striking at the Seed of the woman, corrupting her first son and slaying her second, thus trying to prevent the fulfillment of the protevangelic promise right at the beginning of human history. — Morris, page 139.
When God had sought out Adam after his sin, Adam had responded in confession and repentance, but not Cain. He compounded his wickedness by blatantly lying to God and challenging His right even to question him. …
God, therefore, can no longer speak to Cain in mercy, but only in judgment. Cain had been able to still the hated prophesying voice of his brother, but he could not still the voice of his blood! “The voice of thy brother’s blood crieth unto me from the ground.” For the first time, “blood” is actually mentioned in the Bible in this verse, although its significance had been intimated several times previously. Abel, the type of the seed of the woman, was righteous before God and yet died violently at the hand of the first of the Serpent’s seed. Thus, Abel’s blood crying from the ground is the prototype of all the suffering inflicted on the righteous through the ages by the children of the wicked one. Its climax and fulfillment are seen in the conflict of Satan and Christ on Calvary.
But the blood of Christ “speaketh better things that that of Abel” (Hebrews 12:24). The blood of animals could never really take away sin, though it might enable their skins to be used for a temporary covering. But “the blood of Jesus Christ, God’s Son, cleanseth us from all sin” (1 John 1:7). — Morris, pages 139-140.
I think the verses Morris references are more evidence against the view that Cain’s sacrifice was rejected only because of his attitude. But his view (next quote) is much different than that of Wechsler (below).
God’s punishment of Cain is thus also a type of the ultimate crushing of the head of the Serpent, when he will be separated forever from God in the lake of fire. Cain was forever “driven out from the presence of the Lord”; likewise will all those who obey not the gospel of Christ “be punished with everlasting destruction from the presence of the Lord, and from the glory of his power” (2 Thessalonians 1:9). — Morris, page 140.
Wechsler has a very different take on verses 13-15.
God shows Cain preemptive mercy—that is, He withholds from Cain, despite his lack of remorse, the full penalty that his sin deserves—which is precisely what it takes to crack Cain’s hardened shell of unrepentance and bring him to his knees, pouring out as he does so one of the most heart-rending expressions of remorse and confession to be found in Scripture. (In this respect it is important to bear in mind that the negative New Testament references to Cain in Hebrews 11:4; 1 John 3:12; Jude 1:11 apply specifically to his depravity as described in verses 3-12, not explicitly to the portion thereafter, let alone to his life as a whole.)
Any sense of confession would seem to be quite far—even contrary—to Cain’s statement in this verse as typically translated—to wit, “My punishment is too great to bear!” … In point of fact, the Hebrew word typically translated “punishment” normally means “iniquity” or “evil,” and when used as the object of the verb “bear” always has the idiomatic sense of “bearing away (that is, forgiving) sin”! Thus, for example, these same two words are used by David in Psalm 32:5 in praise of God’s forgiveness: “And Thou didst forgive the iniquity;evil of my sin.” For some reason, however, we recognize David’s legitimate use of this idiom but not Cain’s—and yet David’s sin was even more extensive and premeditated, encompassing adultery, multiple murders (see 2 Samuel 11:16-17), and intentional cover-up (see 2 Samuel 11:22-25). Clearly it is inconsistent not to recognize this same idiom on the part of Cain, which is why it was recognized already in the ancient translations as well as by the majority of early Jewish interpreters that Cain is here expressing deep remorse and confession—i.e., “My iniquity/evil is too great to forgive!”—as prompted by the recognition of God’s preemptive mercy towards him. Nor does verse 14, as is often claimed, contradict this expected idiomatic meaning, for the way in which one understands verse 14 depends largely upon the way in which one understands verse 13. If verse 13 is a complaint, then so too is verse 14; yet if verse 13 is an expression or remorse over the recognition of a sin so wicked that God’s great mercy is unacceptable, verse 14 makes perfect sense as an expression of the just penalty that the sinner not only affirms but in fact desires to be applied! Cain, in other words, is expressing the wish that someone else might execute the penalty of death from which God in His mercy refrained. Viewed in this way, per our straightforward idiomatic reading of verse 13, the latter part of verse 14 should therefore be translated (as is perfectly consistent with the Hebrew grammar): “And may it come about that whoever finds me would kill me!”
As with his parents, so also with Cain God piles grace on top of mercy, bestowing upon His chastised and forgiven child that which he does not deserve—the very definition of grace (whereas mercy entails the withholding of the full punishment that one does deserve). Specifically, in response to Cain’s remorseful recognition of guilt (v.13) and consequent yearning for immediate, full punishment (v.14), God, with the parental foresight of His child’s best in view, gracefully appoints a sign for Cain to indicate that he is under divine protection and so to prevent any others from enacting the full punishment from which God Himself mercifully refrained. In popular culture, however, this “mark of Cain,” as it is commonly referred to, is figuratively employed in exactly the opposite sense to denote anything considered a sign of infamy! It is all the more essential, therefore, that the reader appreciate this sign for what it really is: an abiding supernatural indication of God’s grace and parental care for Cain. The word here for “sign,” in fact, is the same one previously used in Genesis 1:14, as normally, throughout the Bible, to denote miracles—i.e., testimonies to God’s active involvement in human history, usually in connection with a redemptive (and by definition, therefore, gracious) purpose. — Wechsler, pages 120-122.
Wechsler’s take on Cain is brand new to me, but I like it. I find it consistent with the record of God’s grace throughout the Bible.