וְאֶל־קַ֥יִן וְאֶל־מִנְחָת֖וֹ לֹ֣א שָׁעָ֑ה וַיִּ֤חַר לְקַ֙יִן֙ מְאֹ֔ד וַֽיִּפְּל֖וּ פָּנָֽיו׃
but unto Cain and to his offering He had not respect. And Cain was very wroth, and his countenance fell.
Read kabbalistic (mystical) interpretation of Genesis 4:5: and classical mystical sources.