וְאֶל־קַ֥יִן וְאֶל־מִנְחָת֖וֹ לֹ֣א שָׁעָ֑ה וַיִּ֤חַר לְקַ֙יִן֙ מְאֹ֔ד וַֽיִּפְּל֖וּ פָּנָֽיו׃
Каин и его приношение не были угодны. Очень досадно стало Каину, и его лицо поникло.
The Midrash of Philo
Why, when he had begun with Cain, he still mentions him here in the second place, when he says: "And God had respect unto Abel and unto his offerings; but unto Cain and unto his sacrifices he paid no attention?"(Genesis 4:5).
The Midrash of Philo
How it was that Cain became aware that his offering had not pleased God? (Genesis 4:5).