Deuteronomy 18:21
And if thou say in thine heart, How shall we know the word which the LORD hath not spoken?
More from Deuteronomy 18
The priests the Levites, and all the tribe of Levi, shall have no part nor inheritance with Israel: they shall eat the offerings of the LORD made by fire, and his inheritance.
Therefore shall they have no inheritance among their brethren: the LORD is their inheritance, as he hath said
And this shall be the priest's due from the people, from them that offer a sacrifice, whether it be ox or sheep; and they shall give unto the priest the shoulder, and the two cheeks, and the maw.
The firstfruit also of thy corn, of thy wine, and of thine oil, and the first of the fleece of thy sheep, shalt thou give
For the LORD thy God hath chosen him out of all thy tribes, to stand to minister in the name of the LORD, him and his sons for ever.