Or HaChaim on Genesis 14:20/אור החיים על בראשית י״ד:כ׳

1 וברוך אל עליון, "And blessed the Supreme G'd, etc." As already mentioned our sages say that Malki Tzedek was punished for putting G'd second in his list of blessings. He lost his priesthood because of this error. We must try and understand what prompted Malki Tzedek to commit such an error. Perhaps he thought that inasmuch as Abraham had come to recognise G'd without parental or anyone else's guidance, he deserved to receive a blessing first and foremost. Afterwards he blessed the Lord who had found pleasure in a human being such as Abraham. Malki Tzedek may have wanted to teach us that G'd only truly enjoys human beings who have first made it their business to please Him. He expressed this thought by saying: "Blessed Abraham to the Supreme G'd because he made himself be fit to be a servant of the Lord. As a result he is blessed by the Supreme G'd who has committed your enemies into your hands." [according to this Malki Tzedek's error consisted in using chronology as a guideline for the order in which he formulated his blessing. Ed.] Despite the good intention of Malki Tzedek, this was an improper way of blessing. The servant never takes precedence over his Master.