The Lord said unto him, Therefore. — Most of the versions have Not so, which requires only a slight and probable change of the Hebrew text.
Sevenfold. — Cain’s punishment was severe, because his crime was the result of bad and violent passions, but his life was not taken because the act was not premeditated. Murder was more than he had meant. But as any one killing him would mean murder, therefore the vengeance would be sevenfold: that is, complete, seven being the number of perfection. Others, however, consider that Cain’s life was under a religious safeguard, seven being the sacred number of creation. In this we have the germ of the merciful law which set cities of refuge apart for the involuntary manslayer.
The Lord set a mark upon Cain. — This rendering suggests an utterly false idea. Cain was not branded nor marked in any way. What the Hebrew says is, “And Jehovah set,” that is, appointed, “unto Cain a sign, that no one finding him should slay him.” In a similar manner God appointed the rainbow as a sign unto Noah that mankind should never again be destroyed by a flood. Probably the sign here was also some natural phenomenon, the regular recurrence of which would assure Cain of his security, and so pacify his excited feelings.