After the Fall, Adam and Eve gave birth to their first-born son, Cain. As time went by, Adam and Eve gave birth to their second-born son, Abel.
Once they grew up, Cain became a tiller of the ground.
While Abel became a herd flocker.
Cain gave the fruit from the ground to God while Abel gave him the fat from the animals he flocked. However, God accepted Abel's gift and rejected Cain's.
God knew this upset Cain and told him that he should ignore his need to act upon his anger if he would like to be accepted by God. Despite this, out of jealousy, Cain brought Abel into an open field and killed him.
After Cain did this, God asked Cain where Abel was, but Cain lied to God and said he did not know where Abel was and that he was not responsible for Abel.