Therefore whosoever, &c.— As Cain was reserved for exemplary punishment, God delivers him from the apprehension of death, and assures him, that seven-fold vengeance, that is, very severe vengeance, (for the word sevenfold is often put for an indefinite, but great number,) shall be taken on any person who should slay him.
And the Lord set a mark upon Cain, &c.— The literal translation is, and the Lord gave to, or placed before Cain a sign, אות aut, σημειον, LXX, that no one who found him should kill him, i.e.. assured him of this by some external mark or miracle. As the Hebrew and the Septuagint clearly agree in this translation, it puts an end at once to all those frivolous inquiries concerning the mark, as it has been called, which God put upon Cain. See Exodus 10:1.Isaiah 66:19; Isaiah 66:24. It is not improbable, but this sign or miracle was given in the presence of so many, that all were soon informed of the will of the Lord concerning Cain.