Genesis 4

12. a fugitive--condemned to perpetual exile; a degraded outcast; the miserable victim of an accusing conscience.

13, 14. And Cain said . . . My punishment is greater than I can bear--What an overwhelming sense of misery; but no sign of penitence, nor cry for pardon.

14. every one that findeth me shall slay me--This shows that the population of the world was now considerably increased.

15. whosoever slayeth Cain--By a special act of divine forbearance, the life of Cain was to be spared in the then small state of the human race.
set a mark--not any visible mark or brand on his forehead, but some sign or token of assurance that his life would be preserved. This sign is thought by the best writers to have been a wild ferocity of aspect that rendered him an object of universal horror and avoidance.

16. presence of the Lord--the appointed place of worship at Eden. Leaving it, he not only severed himself from his relatives but forsook the ordinances of religion, probably casting off all fear of God from his eyes so that the last end of this man is worse than the first ( Matthew 12:45 ).
land of Nod--of flight or exile--thought by many to have been Arabia-Petræa--which was cursed to sterility on his account.

17-22. builded a city--It has been in cities that the human race has ever made the greatest social progress; and several of Cain's descendants distinguished themselves by their inventive genius in the arts.

19. Lamech took unto him two wives--This is the first transgression of the law of marriage on record, and the practice of polygamy, like all other breaches of God's institutions, has been a fruitful source of corruption and misery.

23, 24. Lamech said unto his wives--This speech is in a poetical form, probably the fragment of an old poem, transmitted to the time of Moses. It seems to indicate that Lamech had slain a man in self-defense, and its drift is to assure his wives, by the preservation of Cain, that an unintentional homicide, as he was, could be in no danger.

26. men began to call upon the name of the Lord--rather, by the name of the Lord. God's people, a name probably applied to them in contempt by the world.