Leviticus 2:4, 11

“If your offering is a grain offering baked in an oven, it must be made of choice flour, but without any yeast. It may be presented in the form of thin cakes mixed with olive oil or wafers spread with olive oil.

“Do not use yeast in preparing any of the grain offerings you present to the LORD, because no yeast or honey may be burned as a special gift presented to the LORD.