וְאֶת־אַהֲרֹ֤ן וְאֶת־בָּנָיו֙ תִּפְקֹ֔ד וְשָׁמְר֖וּ אֶת־כְּהֻנָּתָ֑ם וְהַזָּ֥ר הַקָּרֵ֖ב יוּמָֽת׃ (פ)
And thou shalt appoint Aaron and his sons, that they may keep their priesthood; and the common man that draweth nigh shall be put to death.’
Read halakhic rulings (Jewish law) on Numbers 3:10: and classical halakhic sources.