Genesis 4

Cain and Abel are the first offspring of Adam and Eve.  Cain is a tiller of soil and Abel is a shepherd.  They both make offerings to God of the fruits of their labors.  God accepts Cain's offering of lamb, but rejects Cain's offering of fruit.  God does not understand why Cain is upset at His rejection of Cain's offering, since God still accepts Cain.  Commentary suggest this reflects tension between farmers and nomads.

Cain kills Abel and Abel's blood cries from the earth to God, reflecting perhaps that God considers blood to be sacred.  God gives Cain a mark so that no one takes revenge on Cain to avenge Abel's murder.  Cain goes east of Eden and founds a city.

Adam and Eve have a third son, Seth, whose son the Bible says is the first to worship the "Lord".

Reflecting on the expulsion from Eden, Asimov speculates it might reflect a nostalgia for nomadic times that are no more once agriculture is developed, which required settling in one place.

GOD'S COMMANDMENT(S):

Genesis 4:10-12 - God doesn't come right out and say it, but it appears He has a problem with murder, particularly one borne of jealously, as appears to be the case here.  Penalty is, interestingly at this point, not death but banishment.  Cain is a fugitive and "wanderer of the earth".  Further, he will not be able to grow from the earth any more.

Genesis 4:15 - Murdering Cain is strictly prohibited.  God places a mark on Cain to give the heads up to any potential Cain murderer.  The penalty is "sevenfold", but doesn't explain what that means.  Killed seven times?  Be made a fugitive seven times?

DIFFICULTY OF FOLLOWING COMMANDMENT(S):

Murdering my brother due to jealousy because God liked his sacrifice more than mine hasn't been a problem so far.  First, I don't have a brother.  Second, I don't do old school sacrifices.  Spoiler alert, God doesn't want them, either.

As for murdering Cain, the Bible says he's been gone a long time.  So, even if you wanted to murder him, it's impossible.  So, what exactly this "sevenfold" punishment is will remain a mystery.

GOD'S DEATH TOLL THIS CHAPTER:

Zero

GOD'S RUNNING DEATH TOLL:

Zero