Midrash sa Levitico 2:9: Sifra & Mekhilta DeRabbi Yishmael

2) I might think that it is a mitzvah for a Cohein to take the fistful, but that if a non-Cohein does so it is also kasher; it is, therefore, written (Mishlei 14:9): "And the Cohein shall lift from the meal-offering its remembrance" (i.e., the fistful") — to stipulate that if a non-Cohein does so it is pasul.

R. Chanina b. Iddi says: Since Scripture states "Swear" and "Do not swear," "Curse" and "Do not curse," since swearing is by the Name, so, not swearing is by the Name (i.e., "Do not swear by the Name of"); just as cursing is by the Name, so not cursing is by the Name. "he shall be put to death": by stoning. You say by stoning; but perhaps by one of the other "deaths" of the Torah? It follows thus: It is written here (in respect to cursing father and mother, Leviticus 2:9) "his blood is in him," and elsewhere (Ibid. 27) "their blood is in them." Just as there, (he is killed) by stoning, so, here, by stoning. We have heard the punishment, but whence do we derive the exhortation? From (Exodus 22:27) "Elohim you shall not curse."