Today's reading, Genesis 4-7, is another rich literary expression of the ancient Israelites. I will continue to look at it from the viewpoint of the Documentary Hypothesis.
Chapter 4 is all from the J source, and features the story of Cain and Abel (again showing God taking a personal and individual interest in the characters of the story) and the beginnings of civilization.
Most scholars feel that chapter 5 isn't from J, E, P, or D, but rather is part of a hypothetical document called by some the Book of Generations that the Redactor used to unify the different texts he used in formulating the book of Genesis.
With chapter 6, we get an interesting bit involving the sons of God and the daughters of men, who produced the Nephilim. This leads to God's grief over the increasing wickedness of humanity, and God's regret in creating them in the first place, and his resolve to destroy what he had created. All of this, from verses 1-8, are from the J source. This is followed by the rest of chapter 6, drawn from the P source, which is an account of God's revelation to Noah and his disclosure of his plan to Noah.
Beginning in chapter 7, we get a real taste of the Redactor's artistry, as this entire chapter, along with chapter 8 in tomorrow's reading (the entire depiction of the Flood story), feature him weaving bits of J and P, two separate accounts of the Flood, together into a rich and vibrant tapestry.
At any rate, we see in today's reading that God can become angry, yet remain compassionate (Cain), and is capable of regret, which is a strange quality in a being who is normally depicted as all-powerful and all-knowing.