Moses
Genesis 14:19ESV·traditional attribution

And he blessed him and said, “Blessed be Abram by God Most High, Possessor of heaven and earth;

John Calvin Reformed @genevareformer

19. And he blessed him . Unless these two members of the sentence, ‘He was the priest of God,’ and ‘He blessed,’ cohere together, Moses here relates nothing uncommon. For men mutually bless each other; that is, they wish well to each other. But here the priest of God is described, who, according to the right of his office, sanctifies one inferior and subject to himself.

Matthew Henry Presbyterian @wholebiblehenry

This paragraph begins with the mention of the respect which the king of Sodom paid to Abram at his return from the slaughter of the kings; but, before a particular account is given of this, the story of Melchizedek is briefly related, concerning whom observe, I. Who he was.

Commenting on Genesis 14:17-20

John Gill Reformed Baptist @doctorgill

And he blessed him,.... Melchizedek blessed Abram, which was one part of his office as a priest, to wish and pray for a blessing on others, see Num 6:23, &c. and herein typified Christ, who really blesses or confers blessings on all his people, even spiritual blessings, such as redemption, remission of sins, and justifying righteousness, adoption, and eternal life: and said, blessed be Abram...