Genesis 4:6 Halakhah

וַיֹּ֥אמֶר יְהוָ֖ה אֶל־קָ֑יִן לָ֚מָּה חָ֣רָה לָ֔ךְ וְלָ֖מָּה נָפְל֥וּ פָנֶֽיךָ׃

And the LORD said unto Cain: ‘Why art thou wroth? and why is thy countenance fallen?

Read halakhic rulings (Jewish law) on Genesis 4:6: and classical halakhic sources.