The LORD’s rhetorical question What have you done? is similar in wording and intent to the question put to Eve in 3.13. The trial continues with the judge pointing to the evidence of Cain’s guilt. Since the question is really demanding that Cain explain his behavior, the literal form of the Hebrew will not be appropriate in some languages. A “why?” question will often be better; for example, one translation has “Why have you done this bad thing?” A number of translations also add a term or expression such as “Listen!” which demands the attention of a person while an accusation is made.
When it comes to the actual accusation that the LORD makes against Cain, the Hebrew words translated literally will not be direct enough in many languages. The plain meaning of your brother’s blood is that Cain has killed his brother, and many translations state this directly. For example, “Listen! Your brother is dead. His blood flowed onto the ground, and now it is calling out….” In another case the direct statement is placed at the beginning of the next verse: “Now I’ve got a strong talk for you like this: you killed your brother, and the ground drank up his blood; so now….”
The voice of your brother’s blood is crying to me from the ground: blood in Hebrew is grammatically plural here, and this form generally refers to large amounts of blood or to the blood of a murdered person. See 2 Kgs 9.26; Job 16.18; Isa 26.21; Ezek 24.7-8. According to Num 35.19-21 the “avenger of blood,” or as Good News Translation says, “the dead man’s nearest relative” (Hebrew goʾel hadam), has the responsibility of putting the murderer to death. However, when the nearest relative could not or would not perform his duty, God did it, as the citations above show.
Blood in the expression voice of your brother’s blood is pictured as a person, someone who is crying out for revenge or for justice. In many languages this kind of expression must be changed to a simile; for example, “Your brother’s blood is like a person crying out to me from the ground” or “… like a voice crying out for me to take revenge for him.” See Good News Translation “like a voice calling for revenge.” Although the Hebrew text does not indicate what the blood is calling out for, many languages will need to include this. Revenge or justice are the most likely things being called for, and these will often be expressed in verbal forms. Two examples are “… calling out to me to pay back this wrong” and “… calling me to straighten out [this crime].”
Quoted with permission from Reyburn, William D. and Fry, Euan McG. A Handbook on Genesis. (UBS Helps for Translators). New York: UBS, 1997. For this and other handbooks for translators see here .