And Cain knew his wife
Who this woman was is not certain, nor whether it was his first wife or not; whether his sister, or one that descended from Adam by another of his sons, since this was about the one hundred and thirtieth year of the creation. At first indeed Cain could marry no other than his sister; but whether he married Abel's twin sister, or his own twin sister, is disputed; the Jews say F7, that Cain's twin sister was not a beautiful woman, and therefore he said, I will kill my brother and take his wife: on the other hand, the Arabic writers say F8, that Adam would have had Cain married Abel's twin sister, whom they call Awin; and Abel have married Cain's twin sister, whom they call Azron; but Cain would not, because his own sister was the handsomest; and this they take to be the occasion of the quarrel, which issued in the murder of Abel.
And she conceived and bare Enoch;
which signifies "trained up", not in the true religion, and in the ways of God and godliness, as one of this name descending from Seth was, who is said to walk with God; but in the practices of his father Cain, and in a wicked course of life:
and he builded a city:
for a settlement on earth, thinking of nothing but this world, and the things of it; or to secure himself from being slain by men; or it may be for his amusement, to divert his thoughts from the melancholy scene always presented to his mind, by being thus employed; and his posterity growing numerous, he took this method to keep them together, and that they might be able to defend themselves from the assaults of others. Some render the words, "he was building a city" F9; as if he did not live to finish it; but it looks as if it was finished by him, by what follows:
and called the name of the city, after the name of his son,
not after his own name, which was odious and infamous, but after his son's name, to show his affection to him, and that his name might be continued in ages to come; see ( Psalms 49:11 ) . This was the first city that was built, that we read of. Sir Walter Raleigh conjectures F11 that the Henochii or Heniochi of Pliny, Ptolemy, and other writers, took their name from this city of Henoch, or from the country where it stood, when it was repeopled after the flood, since these people were due east from the garden of Eden.
(For Cain to marry his sister or any other close relation was not harmful as it is today. There would be few if any genetic disorders at this time. However, as time past, the human race accumulated more and more genetic defects, so by the time of Moses, the laws against incest, as given in ( Leviticus 18:1-20:27 ) , were necessary. These laws helped prevent deformed children. Ed.)