'Priesthood' in the Bible

So you shall appoint Aaron and his sons that they may keep their priesthood, but the layman who comes near shall be put to death.”

and that He has brought you near, Korah, and all your brothers, sons of Levi, with you? And are you seeking for the priesthood also?

So the Lord said to Aaron, “You and your sons and your father’s household with you shall bear the guilt in connection with the sanctuary, and you and your sons with you shall bear the guilt in connection with your priesthood.

But you and your sons with you shall attend to your priesthood for everything concerning the altar and inside the veil, and you are to perform service. I am giving you the priesthood as a bestowed service, but the outsider who comes near shall be put to death.”

and it shall be for him and his descendants after him, a covenant of a perpetual priesthood, because he was jealous for his God and made atonement for the sons of Israel.’”