וְאָמַרְתָּ֖ אֲלֵהֶ֑ם בַּהֲרִֽימְכֶ֤ם אֶת־חֶלְבּוֹ֙ מִמֶּ֔נּוּ וְנֶחְשַׁב֙ לַלְוִיִּ֔ם כִּתְבוּאַ֥ת גֹּ֖רֶן וְכִתְבוּאַ֥ת יָֽקֶב׃
Therefore thou shalt say unto them: When ye set apart the best thereof from it, then it shall be counted unto the Levites as the increase of the threshing-floor, and as the increase of the wine-press.
Read halakhic rulings (Jewish law) on Numbers 18:30: and classical halakhic sources.