@DT
Gen.4
[1] And Adam knew Eve his wife; and she conceived, and bare Cain, and said, I have gotten a man from the LORD.
[2] And she again bare his brother Abel. And Abel was a keeper of sheep, but Cain was a tiller of the ground.
[3] And in process of time it came to pass, that Cain brought of the fruit of the ground an offering unto the LORD.
[4] 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:
[5] But unto Cain and to his offering he had not respect. And Cain was very wroth, and his countenance fell.
Why did Abel offer a sacrifice (a sacrificed animal) to God, and why did God accept his sacrifice but not that of his brother Cain?