One question that arises out of the Cain and Abel story that is not explicitly addressed in the text is why God rejected Cain's offering but accepted Abel's. I personally think the reason is inferred in the text; whereas Abel brought from his firstlings, Cain simply brought sacrifices--he did not offer God the best he had to offer.
Apparently, I am not alone in this view. Below are some various ancient interpretive takes.
Philo, The Sacrifices of Cain and Abel, 52: “[Cain’s offering] was ‘of the fruit’ but not ‘of the first fruit.'"
Genesis Rabbah 22:5: “[Cain’s offering] was from the refuse. The matter may be compared to the case of a wicked sharecropper who ate from the first fruits of the figs and handed over to the king the late figs.
Ephraem, Commentary on Gen. 3:2: “Abel chose and brought for sacrifice from the firstborn and the fattest, but Cain brought [merely] the fruits he found at the time . . . [God] chose not to accept his sacrifice from him in order to teach him how it was to be offered up… [Cain] did not bring these on the day of the first fruit offering, but brought the fruit of his land.” -Read More