The Lord told Israel,
“And if you bring as an offering a grain offering baked in the oven, it shall be unleavened cakes of fine flour mixed with oil, or unleavened wafers anointed with oil. But if your offering is a grain offering baked in a pan, it shall be of fine flour, unleavened, mixed with oil. You shall break it in pieces and pour oil on it; it is a grain offering” (Leviticus 2:4-6).
If Israel desired to make a grain offering, that was fine with the Lord, but notice that three times He said it had to be unleavened, and that four times He spoke of the oil that was offered with it.
Leaven often represents sin in the Bible, though not always, and the Lord considered oil to be precious.
Therefore, Israel had to consider the nature of God when they offered Him something, even as we consider the character of a person to whom we give a gift.