Hebrews 7:12-21, 25, 27

And if the priesthood is changed, the law must also be changed to permit it. For the priest we are talking about belongs to a different tribe, whose members have never served at the altar as priests. What I mean is, our Lord came from the tribe of Judah, and Moses never mentioned priests coming from that tribe. This change has been made very clear since a different priest, who is like Melchizedek, has appeared. Jesus became a priest, not by meeting the physical requirement of belonging to the tribe of Levi, but by the power of a life that cannot be destroyed. And the psalmist pointed this out when he prophesied, “You are a priest forever in the order of Melchizedek.” Yes, the old requirement about the priesthood was set aside because it was weak and useless. For the law never made anything perfect. But now we have confidence in a better hope, through which we draw near to God. This new system was established with a solemn oath. Aaron’s descendants became priests without such an oath, but there was an oath regarding Jesus. For God said to him

Therefore he is able, once and forever, to save those who come to God through him. He lives forever to intercede with God on their behalf.

Unlike those other high priests, he does not need to offer sacrifices every day. They did this for their own sins first and then for the sins of the people. But Jesus did this once for all when he offered himself as the sacrifice for the people’s sins.