Hebrews 7:8 (KJV)

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.

Now consider how great this man was, unto whom even the patriarch Abraham gave the tenth of the spoils.

And verily they that are of the sons of Levi, who receive the office of the priesthood, have a commandment to take tithes of the people according to the law, that is, of their brethren, though they come out of the loins of Abraham:

But he whose descent is not counted from them received tithes of Abraham, and blessed him that had the promises.

And without all contradiction the less is blessed of the better.

And as I may so say, Levi also, who receiveth tithes, payed tithes in Abraham.

For he was yet in the loins of his father, when Melchisedec met him.

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.

For he of whom these things are spoken pertaineth to another tribe, of which no man gave attendance at the altar.