Hebrews 9:3-6

Then as you pass through the next curtain you would enter the innermost chamber called, the holiest sanctuary of all. It contained the golden altar of incense and the ark of covenant mercy, which was a wooden box covered entirely with gold. And placed inside the ark of covenant mercy was the golden jar with mystery-manna inside, Aaron’s resurrection rod, which had sprouted, and the stone tablets engraved with the covenant laws. On top of the lid of the ark were two cherubim, angels of splendor, with outstretched wings overshadowing the throne of mercy. But now is not the time to discuss further the significant details of these things. So with this prescribed pattern of worship the priests would routinely go in and out of the first chamber to perform their religious duties.