3,921. The Deputy Kohein Gadol

Hilchos Klei HaMikdash 4:15

A Kohein Gadol is only appointed by the Sanhedrin of 71 judges. He is only anointed by day, as per Leviticus 6:13: “On the day of his anointing....” Similarly, if he was installed only by donning the uniform of the Kohein Gadol, this is done only by day. Two Kohanim Gedolim are not installed together.

Hilchos Klei HaMikdash 4:16

We also appoint a kohein who will assist the Kohein Gadol as a deputy; he is called the s’gan [though here we’ll refer to him as “the Deputy Kohein Gadol"]. He stands to the right hand of the Kohein Gadol at all times, which is a source of honor to him. All the other kohanim report to him.