Psalms 110:4

For he testifieth, Thou art a priest for ever after the order of Melchisedec.

As he saith also in another place, Thou art a priest for ever after the order of Melchisedec.

(For those priests were made without an oath; but this with an oath by him that said unto him, The Lord sware and will not repent, Thou art a priest for ever after the order of Melchisedec:)

And Melchizedek king of Salem brought forth bread and wine: and he was the priest of the most high God.

Whither the forerunner is for us entered, even Jesus, made an high priest for ever after the order of Melchisedec. For this Melchisedec, king of Salem, priest of the most high God, who met Abraham returning from the slaughter of the kings, and blessed him; To whom also Abraham gave a tenth part of all; first being by interpretation King of righteousness, and after that also King of Salem, which is, King of peace; Without father, without mother, without descent, having neither beginning of days, nor end of life; but made like unto the Son of God; abideth a priest continually.

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?

For the law maketh men high priests which have infirmity; but the word of the oath, which was since the law, maketh the Son, who is consecrated for evermore.

God is not a man, that he should lie; neither the son of man, that he should repent: hath he said, and shall he not do it? or hath he spoken, and shall he not make it good?

And hath made us kings and priests unto God and his Father; to him be glory and dominion for ever and ever. Amen.

Even he shall build the temple of the Lord; and he shall bear the glory, and shall sit and rule upon his throne; and he shall be a priest upon his throne: and the counsel of peace shall be between them both.

For when God made promise to Abraham, because he could swear by no greater, he sware by himself, Saying, Surely blessing I will bless thee, and multiplying I will multiply thee. And so, after he had patiently endured, he obtained the promise. For men verily swear by the greater: and an oath for confirmation is to them an end of all strife. Wherein God, willing more abundantly to shew unto the heirs of promise the immutability of his counsel, confirmed it by an oath: That by two immutable things, in which it was impossible for God to lie, we might have a strong consolation, who have fled for refuge to lay hold upon the hope set before us:

The Lord hath sworn in truth unto David; he will not turn from it; Of the fruit of thy body will I set upon thy throne.

My covenant will I not break, nor alter the thing that is gone out of my lips. Once have I sworn by my holiness that I will not lie unto David. His seed shall endure for ever, and his throne as the sun before me.