Genesis 4:9

Defiance grows with sin, and punishment keeps pace with guilt. Adam and Eve fear before God, and acknowledge their sin; Cain boldly denies it, and in reply to the question, "Where is Abel thy brother?" declares, "I know not, am I my brother's keeper?" God therefore charges him with his crime: "What hast thou done! voice of thy brother's blood crying to Me from the earth." The verb "crying" refers to the "blood," since this is the principal word, and the voice merely expresses the adverbial idea of "aloud," or "listen" (Ewald, 317d). דּמים (drops of blood) is sometimes used to denote natural hemorrhage (Lev 12:4-5; Lev 20:18); but is chiefly applied to blood shed unnaturally, i.e., to murder. "Innocent blood has no voice, it may be, that is discernible by human ears, but it has one that reaches God, as the cry of a wicked deed demanding vengeance" (Delitzsch). Murder is one of the sins that cry to heaven. "Primum ostendit Deus se de factis hominum cognoscere utcunque nullus queratur vel accuset; deinde sibi magis charam esse homonum vitam quam ut sanguinem innoxium impune effundi sinat; tertio curam sibi piorum esse non solum quamdiu vivunt sed etiam post mortem" (Calvin). Abel was the first of the saints, whose blood is precious in the sight of God (Psa 116:15); and by virtue of his faith, he being dead yet speaketh through his blood which cried unto God (Heb 11:4).

We have here a full account of the trial and condemnation of the first murderer. Civil courts of judicature not being yet erected for this purpose, as they were afterwards (Gen 9:6), God himself sits Judge; for he is the God to whom vengeance belongs, and who will be sure to make inquisition for blood, especially the blood of saints. Observe, I. The arraignment of Cain: The Lord said unto Cain, Where is Abel thy brother? Some think Cain was thus examined the next sabbath after the murder was committed, when the sons of God came, as usual, to present themselves before the Lord, in a religious assembly, and Abel was missing, whose place did not use to be empty; for the God of heaven takes notice who is present at and who is absent from public ordinances. Cain is asked, not only because there is just cause to suspect him, he having discovered a malice against Abel and having been last with him, but because God knew him to be guilty; yet he asks him, that he may draw from him a confession of his crime, for those who would be justified before God must accuse themselves, and the penitent will do so. II. Cain's plea: he pleads not guilty, and adds rebellion to his sin. For, 1. He endeavours to cover a deliberate murder with a deliberate lie: I know not. He knew well enough what had become of Abel, and yet had the impudence to deny it. Thus, in Cain, the devil was both a murderer and a liar from the beginning. See how sinners' minds are blinded, and their hearts hardened by the deceitfulness of sin: those are strangely blind that think it possible to conceal their sins from a God that sees all, and those are strangely hard that think it desirable to conceal them from a God who pardons those only that confess. 2. He impudently charges his Judge with folly and injustice, in putti…

4:9 Where is your brother? The questions God asked Cain (4:6, 9, 10) recall those that God asked Cain’s parents (3:9-13). In both cases, humans put up evasive answers (cp. 3:12-13). Cain’s answer is shockingly defiant—another clue that the problem with his token offering was the attitude that lay behind it.