Adam knew his wife Eve intimately, and she conceived and gave birth to Cain. She said, "I have had a male child with the Lord's help."
References for Genesis 4:1
Then she also gave birth to his brother Abel. Now Abel became a shepherd of a flock, but Cain cultivated the land.
In the course of time Cain presented some of the land's produce as an offering to the Lord.
References for Genesis 4:3
And Abel also presented [an offering]-some of the firstborn of his flock and their fat portions. The Lord had regard for Abel and his offering,
but He did not have regard for Cain and his offering. Cain was furious, and he was downcast.
References for Genesis 4:5
Then the Lord said to Cain, "Why are you furious? And why are you downcast?
References for Genesis 4:6