Heb 7:12 says there was a change in the law because of a better mediator.
Heb 7:12 For the priesthood being changed, there is made of necessity a change also of the law.
Ye do err, not knowing the scriptures, even quoting out of context:
Hebrews 7:11 KJV - 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?
Hebrews 7:12 KJV - For the priesthood being changed, there is made of necessity a change also of the law.
The Ten Commandments were spoken and written by God, before there was ever an "Levitical Priesthood". The Ten Commandments have nothing to do with calling, ordering, or making priests. The Ten Commandments are eternal. The Ten Commandments were not given "under" the Levitical Priesthood on earth, but given from Heaven, above all this earth.
Exodus 20:22 KJV - And the LORD said unto Moses, Thus thou shalt say unto the children of Israel, Ye have seen that I have talked with you from heaven.
It is written:
Secondly, notice these words, for they are not in contradiction to the other.
[1] "Till heaven and earth pass, one jot or one tittle shall in no wise pass from the law, till all be fulfilled."
[2] "...the priesthood being changed, there is made of necessity a change also of the law."
Nowhere, will anyone find that the Ten Commandments were given
"under" the Levitical Priesthood. The Ten Commandments were
known and given before the Levitical Priesthood was ever called into existence by God [just read the chronological order of the OT texts in Exodus, etc], for transgression of that very Holy Law. Notice that these texts deal with "the commandment" [singular], in its "weakness" and "unprofitableness", which can in no way describe God's "perfect", "Holy", "just" and "good" Ten Commandments, which are even
"for ever and ever"" [Psalms 111:7-8; Psalms 119:44].
Hebrews 7:18 KJV - For there is verily a disannulling of the commandment going before for the weakness and unprofitableness thereof.
In further consideration, there would not have been any need for such a priesthood of type without the transgression of the Ten Commandments in the first place [for sin is sill the transgression of the Law, 1 John 3:4].
The Levitical Priesthood was called into existence as a type/shadow to point to that/Him [Jesus] which was needed for transgression of the "holy, just and good" Law [Ten Commandments].
Christ Jesus says, that not even
"one jot or tittle" [smallest portions, letter] shall
"pass from the Law" "till heaven and earth pass" and
"till all be fulfilled". Well that obviously has not happened yet [no matter what anyone declares], just see Peter's words, or John's, or Jesus' etc. [Matthew 24:35; Mark 13:31; Luke 21:33; 2 Peter 3:10]
Paul says by inspiration [Holy Spirit], that
"...priesthood..." is
"changed" [from Levitical, to Melchizedek] and
"the law" [laws of shadows and types given "under" the Levitical Priesthood, not the Ten Commandments which existed before it] also needed a
"change", and he further speaks about a "change" on a particular typicalogical/shadowy law, when he says a
"...disannulling of the commandment" [singular, "εντολης G1785 N-GSF"] "going before for the weakness and unprofitableness thereof." [Hebrews 7:18].
For the laws of shadows and types are left written as they have been, not to be taken out of the scriptures, because they
still serve several functions, a few of which are listed here.
[1] For any which seek to save themselves by any law [ceremonial/typological or other; it is an utter impossibility, it remains for them, that they might remain under the curse,
until they by God's grace repent, and give up on such a futile attempt and come to Christ Jesus and salvation by grace through faith [For
as many as are of the works of the law are
under the curse: for it is written,
Cursed [is] every one that continueth not in all things which are written in the book of the law to do them. Galatians 3:10]
[2] For other aspects and examples were written for our admonition, learning, instruction in righteouness, correction, doctrine, reproof, etc, which are still needed by the whole world, especially the Christian, as they were given for a lesson book in picture [Now
all these things happened unto them for ensamples: and
they are written for our admonition, upon whom the ends of the world are come. 1 Corinthians 10:11 and
All scripture [is] given by inspiration of God, and [is]
profitable for doctrine, for
reproof, for
correction, for
instruction in righteousness: 2 Timothy 3:16]
[3] For examples of what Jesus Christ Himself would do, in fulfillment of prophecy and typology, etc, in His perfect ministry and life, here on earth and in His ascension into the Heavenly, and in the earth made new to come, and into eternity future [texts which teach this, all could not possibly be listed here: And
beginning at Moses and all the prophets, he expounded unto them in all the scriptures the things concerning himself. Luke 24:27
[4] For to shew that we still need those things, not in type/shadow, but in the reality Christ Jesus, which is the reality/substance [Which are
a shadow of things to come;
but the body [is] of Christ. Colossians 2:17 and
Which [was] a figure for the time then present, in which were offered both gifts and sacrifices, that could not make him that did the service perfect, as pertaining to the conscience; Hebrews 9:9; [Which stood] only in meats and drinks, and divers washings, and carnal ordinances,
imposed [on them] until the time of reformation. Hebrews 9:10;
But Christ being come an high priest of good things to come,
by a greater and more perfect tabernacle, not made with hands, that is to say, not of this building; Hebrews 9:11]
So the
"change" was already foretold in prophecy and in type and remains there, it is not
"passed away". We still need these things, not in shadow, but in the reality, as was already told from before. The type/shadow was never a permanent institution, but a temporary picturebook of the True, that the plan of salvation might be understood in the reality Christ Jesus.
We still need the blood of the sacrifice and the sacrifice, even the Lamb, etc, but not in animals, but in the True Lamb of God,etc - Jesus Christ.
We still need a Highpriest ministering, but not of the house of Levi, but of the true, after the order of Melchizedek.
We still need the Sanctuary/Temple, not of the earthly built by mens hands, but of the Heavenly Temple of which God Himself built.
We still need the Day of Atonement service, not in the shadow of literal animals and once at the end of every year, but in the true Day of Atonement [even as there was the True Passover, the True unleavened, the True Firstfruits, the True Pentecost, etc..] by the Great Highpriest Jesus Christ in the Heavenly Most Holy.
So the law of needing a Great High Priest, etc is not passed away, but merely changed [as was foretold] from shadow to reality. Therefore the
"commandment" [singular] was "disannulled", to take of the Levites a Highpriest, for they were merely instituted as a temporary shadow/type, and so we still need of a Highpriest, but after the order of Melchizedek, which existed before the Levitical one.
The sacrifice of animals had
"weakness" and
"unprofitableness", in that it could not actually
"take away sins" [Hebrews 10:4], not that we could not still learn from the type in how Christ Jesus would be our sacrifice, and not that we do not still need the true sacrifice [of course we need Him!], etc.
And walk in love, as Christ also hath loved us, and hath given himself for us an offering and a sacrifice to God for a sweetsmelling savour. Ephesians 5:2
Purge out therefore the old leaven, that ye may be a new lump, as ye are unleavened. For even Christ our passover is sacrificed for us: 1 Corinthians 5:7
Therefore, we may conclude that the law of sacrifice and priesthood did not "pass away", but was "change[d]" from shadow to reality as was necessary and as foretold and the Ten Commandments begin given above it all, from Heaven, by the direct voice of God Himself, and from His own fiery finger, is eternal.