ויאמר קין אל הבל אחיו. פי' שסיפר לו דברי הקב"ה, ומה שאמר לו, והראה לו שחרה לו היטב, על אשר לא שעה אליו, כמו אל הבל, ושמח הבל, ויקם קין על הבל אחיו ויהרגהו בקנאתו. ובשם ה"ר יוסף קרא שמעתי, ויאמר קין וגו', כי מתחלה הי' ירא, מפני קין מכעסו, והיה נשמר ממנו, וכשאמר לו יתברך, הלא אם תיטיב שאת, מיד, ויאמר קין אל הבל אחיו, שאמר לו, כי הקב"ה נתרצה לו, ושב מעליו אפו, ומשם ואילך חשב הבל, שכבר נתקררה דעתו, ולא נשמר ממנו מלילך עמו: ויאמר קין אל הבל אחיו, “Kayin said to his brother Hevel;” seeing that the Torah does not elaborate on the content of Kayin’s words, we must assume that he told his brother about what G–d had said to him. (verse 6-7) He made it plain to his brother that he was very upset that G–d had not seen fit to accept his offering as He had done with Hevel’s offering. Hevel reacted to G–d having criticised Kayin with joy. When Kayin saw that his brother had been glad that he had been criticised by G–d, he arose with the intent of killing him. (second half of this verse). His motive was plain jealousy. Our author cites an additional or different interpretation of the incomplete sentence: “Kayin said to his brother Hevel,” which he had heard in the name of Rabbi Joseph Kara (turn of 11th century, not to be confused with Joseph Karo author of Shulchan Aruch, of Safed who lived during the most of the 16th century). that initially Hevel, having heard from Kayin what G–d had said to him, was afraid of him seeing that his brother was so angry, and remained on guard against him. When Kayin told him that G–d had held out hope for him by promising that He would relate to him with fondness if he changed his ways, Hevel dropped his guard feeling certain that Kayin would indeed change his ways. When Kayin spoke to him in a friendly mien, i.e. ויאמר, he thought that this was proof that Kayin had changed. He therefore dropped his guard with fatal consequences for himself.