The רבי of Gur, רבי יצחק מאיר, asked what is the פירוש of the question ה׳ asked of קין after he killed his brother: “למה נפלו פניך?” Why wouldn’t he be sad after ה׳ didn’t accept his מנחה? The רבי answered: “The רבונו של עולם asked קין ‘Why are you sad? Is it because I didn’t accept your מנחה or is it because I accepted the מנחה of your brother?’”
06/10/2021