Chapter 18 - Of Adam's Knowing Eve

When Adam and Eve went forth from Paradise, they were both virgins.
After thirty years Adam knew Eve his wife, and she conceived and brought forth Cain together with his sister Kelêmath at one birth. And after thirty years Eve conceived and brought forth Abel and Lebôdâ his sister at one birth.
And when they arrived at the age for marriage, Adam wished and intended to give Abel's sister to Cain and Cain’s sister to Abel; but Cain desired his own sister more than Abel's. Both (i.e. Kelêmath and Lebôdâ) were his sisters, but because of their birth at one time I have called them thus. Now Cain's sister was exceedingly beautiful.
The two brothers made an offering to God because of this matter. Abel, because he was a shepherd, offered up of the fat firstlings of his flock in great love, with a pure heart and a sincere mind. Cain, because he was a husbandman, made an offering of some of the refuse of the fruits of his husbandry with reluctance. He made an offering of ears of wheat that were smitten by blight; but some say of straw only. And the divine fire came down from heaven and consumed the offering of Abel, and it was accepted; while the offering of Cain was rejected.
And Cain was angry with God, and envied his brother; and he persuaded his brother to come out into the plain, and slew him. Some say that he smashed his head with stones, and killed him; and others say that Satan appeared to him in the form of wild beasts that fight with one another and slay each other. At any rate, he killed him, whether this way or that way.
Then God said to Cain, 'Where is Abel thy brother?'