But the tithes of the children of Israel, which they offer as an heave offering unto the Lord, I have given to the Levites to inherit: therefore I have said unto them, Among the children of Israel they shall have no inheritance. (Numbers 18:24)
That the people might be willing to give their tithes to the Levites, these are represented as “an heave offering” unto Jehovah. This does not mean that the ritual of heave offerings was followed, but rather that the tithes were to be offered to God, and that He in turn gave them to the Levites.