Numbers 18:27-32

²⁷And your separation shall be reckoned to you as the corn from the threshing-floor, and as the wine of the wine-press;

²⁸So shall you set apart the separation before the Lord of all your tenths that you receive from the sons of Israel, and give thereof a separation before the Lord unto Aharon the priest.

²⁹Of all that is given to you ye shall set apart every separation for the Lord, of all the best of it, to be the hallowed portion thereof.

³⁰And say thou to them, When you have set apart the finest of it, it shall be reckoned to the Levites as the produce of the threshing-floor, and as the fruitage for the wine-press;

³¹And you may eat it in every place, you and the men of your house; for it is a remuneration to you on account of your service in the tabernacle of ordinance.

³²And you shall not contract guilt by it in your setting apart the finest of it, nor profane the consecrated things of the children of Israel.