Musar zu Bereschit 14:18

And this is the language of Zohar Chadash in Parshath Lech Lecha: "R. Avahu said: 'Come and see how great is the man who causes another to repent. Whence do we know this? From Bereshith 14:18: "And Malki Tzedek, king of Shalem" R. Chiyya Rabbah taught: 'When the soul of the tzaddik who causes others to repent leaves his body, Michael, the great prince, who presents the souls of tzaddikim before his Creator, goes out and greets that tzaddik, as it is written: "And Malki Tzedek" — this is Michael, the chief of the keepers of the gates of righteousness; "the king of Shalem" — this is the Heavenly Jerusalem. (Ibid.): "brought out bread and wine" — he came forward to him and said: 'Come in peace.'" And in 62b:

When I wrote that Abraham gave to Malki Tzedek both the מעשר and the תרומה, you may ask that one does not give מעשר to a priest but to a Levite, and that Malki Tzedek was a priest! The Arizal explains that Aaron was a re-incarnation of Malki Tzedek's soul, and that the prophet Samuel was a re-incarnation of Aaron's soul. This is hinted at by G–d when He said to Moses in Exodus 4,14: "Is there not Aaron your brother the Levite?" The prophet Samuel was a Levite, and Malki Tzedek was another name for שם the son of Noach. You will note that the first half of the name of the prophet שמואל is שם. Malki Tzedek, in addition to being a priest, as the Torah describes him in Genesis 14,18, was also a Levite, at least potentially.

I have already explained how all the attachment to G–d is achieved by means of Torah, and how all the "crowns" have as their purpose to further that attachment. The "crown" of Royalty may therefore be viewed as conferred due to the Torah. The tribe of Levi, which represents the "crown" of Priesthood, is described in Deuteronomy 33,10 as performing the function: יורו משפטיך ליעקב ותורתך לישראל, "They will instruct Jacob in Your laws and Israel in Your Torah." Clearly, this "crown" too is conferred thanks to the Torah. Concerning the Kingdom of the house of David, we find that our sages comment on the verse in Samuel I 16, 18: וה' עמו "G–d was with him," by remarking that the שכינה accompanied David wherever he went. The "crown" of Royalty is part of the "crown" of the Priesthood since the Kingdom of the seed of Yehudah was rooted in Tamar the daughter of Shem, who had been a High Priest already in the days of Abraham (an alternate name for Malki Tzedek mentioned in Genesis 14,18, as per Nedarim 32). When Israel later on sent spies to the land of Canaan prior to conquering it under the leadership of Joshua, the latter sent out Pinchas and Caleb. Caleb was from the tribe of Yehudah who represented Royalty, whereas Pinchas represented the Priesthood. (Cf. Bamidbar Rabbah 16, 4 commenting on Joshua 2, 1) Something of a similar nature will occur in the future when the prophet Elijah will represent the Priesthood before the arrival of the Messiah, and the Messiah will be Royalty incarnate. Pinchas is identified with the prophet Elijah.