Now Adam knew Eve his wife, and she conceived and bore Cain, saying, “I have gotten a man with the help of the Lord.” And again, she bore his brother Abel. Now Abel was a keeper of sheep, and Cain a worker of the ground.
cain followed adam in occupation and disregard for zthe word
Genesis 4:3–5 NASB95
So it came about in the course of time that Cain brought an offering to the Lord of the fruit of the ground.Abel, on his part also brought of the firstlings of his flock and of their fat portions. And the Lord had regard for Abel and for his offering;but for Cain and for his offering He had no regard. So Cain became very angry and his countenance fell.
in the course of tim implying that the sacrifices thus far have been acceptabke
God required them to bring a sacrifice becaue it reminded them of the penalty of sin
