Genesis 14:18
16 He retrieved all the stolen property. He also brought back his nephew Lot and his possessions, as well as the women and the rest of the people. 17 After Abram returned from defeating Kedorlaomer and the kings who were with him, the king of Sodom went out to meet Abram in the Valley of Shaveh (known as the King’s Valley). 18 Melchizedek king of Salem brought out bread and wine. (Now he was the priest of the Most High God.) 19 He blessed Abram, saying, “Blessed be Abram by the Most High God, Creator of heaven and earth. 20 Worthy of praise is the Most High God, who delivered your enemies into your hand.” Abram gave Melchizedek a tenth of everything.
Nedarim 32b
Babylonian TalmudAs it is stated: “And he blessed him and said: Blessed be Abram of God Most High, Maker of heaven and earth, and blessed be God the Most High” (Genesis 14:19–20). Abraham said to him: And does one place the blessing of the servant before the blessing of his master? You should have blessed God first. Immediately the Holy One, Blessed be He, gave the priesthood to Abraham, as it is stated: “The Lord says to my lord: Sit at My right hand, until I make your enemies your footstool” (Psalms 110:1), and afterward it is written: “The Lord has sworn, and will not repent: you shall be a priest forever, because you are a king of righteousness [al divrati malki tzedek]” (Psalms 110:4), which is explained homiletically to mean: Due to the improper words [divrati] of Melchizedek, the offspring of Abraham shall be priests of God forever. The Gemara comments: And this is as it is written: “And he was priest of God the Most High” (Genesis 14:18), which emphasizes that he, Melchizedek, is a priest, but his children will not be priests.
Notes and References
"... The Jewish reaction to the Christian appropriation of Melchizedek is twofold and each trend is diametrically opposed to the other: either Melchizedek is relocated well within Judaism or or his importance is downplayed. According to the midrash, Melchizedek was born circumcised. The widely attested identification of Melchizedek with Noah’s son Shem in the Targum and in Rabbinic literature counters both the claim of a heavenly figure ‘without father or mother’ and of Melchizedek being uncircumcised. Nevertheless this is not yet conclusive proof that this Jewish motif originated as a form of polemics with Christianity for it may have served an exegetical purpose, explaining Shem still being alive at the time of Abraham (Genesis 11:11). However, the following Talmudic text is undoubtedly polemical against Christian exaltation of Melchizedek (b. Nedarim 32b) ... The elevation of Abraham at the expense of Melchizedek is so foreign to the description of Melchizedek in Scripture that a polemical intent may be assumed. Melchizedek’s priesthood is no longer eternal, but transferred to Abraham already from the outset ..."
Poorthuis, Marcel Saints and Role Models in Judaism and Christianity (pp. 97-120) Brill, 2004