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.