Numbers 18:26
Thus speak unto the Levites, and say unto them, When ye take of the children of Israel the tithes which I have given you from them for your inheritance, then ye shall offer up an heave offering of it for the LORD, even a tenth part of the tithe.
Thus speak unto the Levites, and say unto them,.... Aaron was to tell them what a provision would be made for them on account of their service, but Moses was to inform them what part Aaron was to have out of it:
When ye take of the children of Israel the tithes which I have given you from them for your inheritance; which was done at the time of their harvest, and of the ingathering of the fruits of the earth:
then ye shall offer up an heave offering of it for the LORD; in token of gratitude for the liberal provision he had made for the maintenance of them:
even a tenth part of the tithe; a tenth part out of the tenth of the produce of the land of Israel.