Hebrews 7:11

Now if there was perfection through the Levitical priesthood (for under it hath the people received the law), what further need was there that another priest should arise after the order of Melchizedek, and not be reckoned after the order of Aaron?

Hebrews 8:7

For if that first covenant had been faultless, then would no place have been sought for a second.

Galatians 2:21

I do not make void the grace of God: for if righteousness is through the law, then Christ died for nought.

Hebrews 5:6

as he saith also in another place, Thou art a priest for ever After the order of Melchizedek.

Hebrews 7:17-19

for it is witnessed of him, Thou art a priest for ever After the order of Melchizedek.

Galatians 4:3

So we also, when we were children, were held in bondage under the rudiments of the world:

Galatians 4:9

but now that ye have come to know God, or rather to be known by God, how turn ye back again to the weak and beggarly rudiments, whereunto ye desire to be in bondage over again?

Colossians 2:10-17

and in him ye are made full, who is the head of all principality and power:

Hebrews 5:10

named of God a high priest after the order of Melchizedek.

Hebrews 6:20

whither as a forerunner Jesus entered for us, having become a high priest for ever after the order of Melchizedek.

Hebrews 7:15

And what we say is yet more abundantly evident, if after the likeness of Melchizedek there ariseth another priest,

Hebrews 7:21

(for they indeed have been made priests without an oath; but he with an oath by him that saith of him, The Lord sware and will not repent himself, Thou art a priest for ever);

Hebrews 8:10-13

For this is the covenant that I will make with the house of Israel After those days, saith the Lord; I will put my laws into their mind, And on their heart also will I write them: And I will be to them a God, And they shall be to me a people:

Hebrews 10:1-4

For the law having a shadow of the good things to come, not the very image of the things, can never with the same sacrifices year by year, which they offer continually, make perfect them that draw nigh.

Treasury of Scripture Knowledge

Summary

If therefore perfection were by the Levitical priesthood, (for under it the people received the law,) what further need was there that another priest should rise after the order of Melchisedec, and not be called after the order of Aaron?

General references

Bible References

Perfection

Hebrews 7:18
For there is a disannulling of a foregoing commandment because of its weakness and unprofitableness
Hebrews 8:7
For if that first covenant had been faultless, then would no place have been sought for a second.
Hebrews 10:1
For the law having a shadow of the good things to come, not the very image of the things, can never with the same sacrifices year by year, which they offer continually, make perfect them that draw nigh.
Galatians 2:21
I do not make void the grace of God: for if righteousness is through the law, then Christ died for nought.
Galatians 4:3
So we also, when we were children, were held in bondage under the rudiments of the world:
Colossians 2:10
and in him ye are made full, who is the head of all principality and power:

What

Hebrews 7:26
For such a high priest became us, holy, guileless, undefiled, separated from sinners, and made higher than the heavens;

Another

Hebrews 7:15
And what we say is yet more abundantly evident, if after the likeness of Melchizedek there ariseth another priest,
Hebrews 5:6
as he saith also in another place, Thou art a priest for ever After the order of Melchizedek.
Hebrews 6:20
whither as a forerunner Jesus entered for us, having become a high priest for ever after the order of Melchizedek.

General references

Numbers 20:26
and strip Aaron of his garments, and put them upon Eleazar his son: and Aaron shall be gathered unto his people , and shall die there.

American Standard Version Public Domain