Genesis 4:4-5

Genesis 4:4-5

[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. 

What is the context of Genesis 4:4-5?