"You are to clothe them -- your brother Aaron and his sons with him -- and anoint them and ordain them and set them apart as holy, so that they may minister as my priests.

Then you are to clothe Aaron with the holy garments and anoint him and sanctify him so that he may minister as my priest.

"Take Aaron and his sons with him, and the garments, the anointing oil, the sin offering bull, the two rams, and the basket of unleavened bread,

Whom he consecrated

"Now this is what you are to do for them to consecrate them so that they may minister as my priests. Take a young bull and two rams without blemish;

For the law appoints as high priests men subject to weakness, but the word of solemn affirmation that came after the law appoints a son made perfect forever.

General references

You must write Aaron's name on the staff of Levi; for one staff is for the head of every tribe.

They were assigned to the Kohathite clans of the Levites who were descendants of Aaron, for the first lot belonged to them.

And no one assumes this honor on his own initiative, but only when called to it by God, as in fact Aaron was.