Psalms 110:1-4, "יהוה said to my Master, “Sit at My right hand, Until I make Your enemies a footstool for Your feet.” יהוה sends Your mighty sceptre out of Tsiyon. Rule in the midst of Your enemies! Your people volunteer in the day of Your might, In the splendours of set-apartness! From the womb, from the morning, You have the dew of Your youth! יהוה has sworn and does not relent, “You are a priest forever According to the order of Malkitseḏeq.”
Hebrews 5:5-6, "So also the Messiah did not extol Himself to become High Priest, but it was He who said to Him, “You are My Son, today I have brought You forth. As He also says in another place, “You are a priest forever according to the order of Malkitseḏeq,”[/QUOTE\
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 priesthood being changed, there is made of necessity a change also of the law.
Hebrews 7:11-12 KJV