Leviticus 16:2-3

2and the  Lord said to Moses, “Tell Aaron your brother not to acome at any time into the Holy Place inside the veil, before the mercy seat that is on the ark, so that he may not die. For bI will appear in the cloud over the mercy seat. 3But in this way Aaron shall come into the Holy Place: cwith a bull from the herd for a sin offering and da ram for a burnt offering.
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