Leviticus 16-17

“Tell Aaron your brother not to come at any time into the Holy Place inside the veil …so that he may not die” (16:2).  After Aaron’s sons took their priestly duties lightly and died, Aaron was reminded not to enter the Holy Place casually.  God Himself was there, in a cloud (v2).  Once a year, the high priest performed sacrifices of atonement for himself and the people, and only then could he enter safely. Only then could he have access to the mercy seat.

Yearly atonement was necessary “because of all their sins” (16:34).  But Jesus gave his life once to cleanse us permanently, and with Him we can enter the Holy Place without fear (Heb 9).