The Gemara in Shabbos (88b-89a) relates that when Moshe climbs
“Tell me,” Moshe asks them, “I notice that it says in the Torah, ‘do not kill,’ ‘do not steal,’ and ‘do not commit adultery.’ Do you angels have jealousy up here? Do you have an evil inclination here in the heavens?”
Immediately the angels acquiesce to God’s wishes to grant the Torah to the Jewish people.
Kli Yakkar uses this story to explain a curious detail about one of the sacrifices offered on Shavuos. The Torah tells us that on the holiday of fiftieth day of the Omer (which we call Shavuos), the Jewish people must offer a מנחה חדשה – a new grain sacrifice – to God. While the Omer offering brought on Pesach consists of smaller measurement of barley, this new offering must consist of fine flour, and חמץ תאפינה – must be baked as Chametz. Why must it specifically be Chametz?
Many commentators explain that chametz represents the yetzer hara -- the evil inclination. As Moshe argued on