Hebrews 8:4

Now if He were on earth, He would not be a priest at all, since there are those who offer the gifts according to the Law;

Numbers 16:40

as a reminder to the sons of Israel that no layman who is not of the descendants of Aaron should come near to burn incense before the Lord; so that he will not become like Korah and his company—just as the Lord had spoken to him through Moses.

Numbers 17:12-13

Then the sons of Israel spoke to Moses, saying, “Behold, we perish, we are dying, we are all dying!

Numbers 18:5

So you shall attend to the obligations of the sanctuary and the obligations of the altar, so that there will no longer be wrath on the sons of Israel.

2 Chronicles 26:18-19

They opposed Uzziah the king and said to him, “It is not for you, Uzziah, to burn incense to the Lord, but for the priests, the sons of Aaron who are consecrated to burn incense. Get out of the sanctuary, for you have been unfaithful and will have no honor from the Lord God.”

Hebrews 5:1

For every high priest taken from among men is appointed on behalf of men in things pertaining to God, in order to offer both gifts and sacrifices for sins;

Hebrews 7:11-15

Now if perfection was through the Levitical priesthood (for on the basis of it the people received the Law), what further need was there for another priest to arise according to the order of Melchizedek, and not be designated according to the order of Aaron?

Hebrews 11:4

By faith Abel offered to God a better sacrifice than Cain, through which he obtained the testimony that he was righteous, God testifying about his gifts, and through faith, though he is dead, he still speaks.

Treasury of Scripture Knowledge

Summary

For if he were on earth, he should not be a priest, seeing that there are priests that offer gifts according to the law:

Gifts

Bible References

He should

Hebrews 7:11
Now if perfection was through the Levitical priesthood (for on the basis of it the people received the Law), what further need was there for another priest to arise according to the order of Melchizedek, and not be designated according to the order of Aaron?
Numbers 16:40
as a reminder to the sons of Israel that no layman who is not of the descendants of Aaron should come near to burn incense before the Lord; so that he will not become like Korah and his company—just as the Lord had spoken to him through Moses.
Numbers 17:12
Then the sons of Israel spoke to Moses, saying, “Behold, we perish, we are dying, we are all dying!
Numbers 18:5
So you shall attend to the obligations of the sanctuary and the obligations of the altar, so that there will no longer be wrath on the sons of Israel.
2 Chronicles 26:18
They opposed Uzziah the king and said to him, “It is not for you, Uzziah, to burn incense to the Lord, but for the priests, the sons of Aaron who are consecrated to burn incense. Get out of the sanctuary, for you have been unfaithful and will have no honor from the Lord God.”

Gifts

Hebrews 11:4
By faith Abel offered to God a better sacrifice than Cain, through which he obtained the testimony that he was righteous, God testifying about his gifts, and through faith, though he is dead, he still speaks.