Genesis 4:29

"And Adam knew Eve his wife; and she conceived, and bare Cain, and said, I have gotten a man from the LORD. And she again bare his brother Abel. And Abel was a keeper of sheep, but Cain was a tiller of the ground. And in process of time it came to pass, that Cain brought of the fruit of the ground an offering unto the LORD. And Abel, he also brought of the firstlings of his flock and of the fat thereof. And the LORD had respect unto Abel and to his offering: But unto Cain and to his offering he had not respect. And Cain was very wroth, and his countenance fell.

And the LORD said unto Cain, Why art thou wroth? and why is thy countenance fallen? If thou doest well, shalt thou not be accepted? and if thou doest not well, sin lieth at the door. And unto thee shall be his desire, and thou shalt rule over him.

And Cain talked with Abel his brother: and it came to pass, when they were in the field, that Cain rose up against Abel his brother, and slew him. And the LORD said unto Cain, Where is Abel thy brother? And he said, I know not: Am I my brother's keeper? And he said, What hast thou done? the voice of thy brother's blood crieth unto me from the ground. And now art thou cursed from the earth, which hath opened her mouth to receive thy brother's blood from thy hand; When thou tillest the ground, it shall not henceforth yield unto thee her strength; a fugitive and a vagabond shalt thou be in the earth."

Even as God continues to provide for the first few generations of humans, the consequences of human sin and spiritual separation from God become obvious. Adam and Eve start having children, including Cain and his brother Abel. Eve knew she was directly responsible for the pain she experienced in childbirth (Genesis 3:16), but she still gives God credit for helping her to bear Cain.

Cain and Abel grow up and choose different professions, both apparently maintaining a relationship with God. When both bring offerings to God, He shows favor on Abel and his offering of the fat of one of his slaughtered lambs. God does not, however, show favor on Cain or his offering of the fruit of the crops from the fields he has been working. This might have been due to a poor attitude on the part of Cain. Or, Cain's offering might have been smaller or less sacrificial than it ought to have been. For whatever reason, God does not find his efforts pleasing.

Cain becomes angry, and envious of his brother Abel. God warns Cain that sin is crouching at the door and Cain must master it. If sin and temptation are allowed to be in control, tragedy is soon to follow. Instead, Cain meets Abel in a field and murders him. This first recorded human death, and murder, once again sees God confronting His own creation over their sin. He comes to Cain and says that He can hear Abel's blood crying to Him from the ground.

In a scene similar to God's curses on Adam and Eve after their sin in the garden, God punishes Cain by cursing him from the ground. It will never again give him crops. God also sends Cain away from his family to wander the earth. Cain complains that without God's protection someone will surely kill him in retribution of Abel's murder. So, God marks Cain somehow for his own protection and promises to avenge seven-fold anyone who kills him.

Cain wanders to the land of Nod (which means "wander"). He marries, helps to build his city, and has a son, who has a son, who has a son. Lamech, Cain's descendent who was seven generations from Adam, seems to share Cain's rebellion, arrogance, and violence.

Adam and Eve have another son, though. Eve sees Seth as God's replacement for lost Abel. Seth and his line become known as people who rely on God and call upon His name.