Numbers 18:27-30

18:27 And your raised offering will be credited to you as though it were grain from the threshing floor or as new wine from the winepress. 18:28 Thus you are to offer up a raised offering to the Lord of all your tithes which you receive from the Israelites; and you must give the Lord’s raised offering from it to Aaron the priest. 18:29 From all your gifts you must offer up every raised offering due the Lord, from all the best of it, and the holiest part of it.’

18:30 “Therefore you will say to them, ‘When you offer up the best of it, then it will be credited to the Levites as the product of the threshing floor and as the product of the winepress.