וְאֶל־קַ֥יִן וְאֶל־מִנְחָת֖וֹ לֹ֣א שָׁעָ֑ה וַיִּ֤חַר לְקַ֙יִן֙ מְאֹ֔ד וַֽיִּפְּל֖וּ פָּנָֽיו׃
און צו קַיִנען און צו זײַן קרבן האָט ער זיך ניט געקערט. האָט קַיִנען זײער געערגערט, און זײַן פּנים איז אַראָפּגעפֿאַלן.
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).