Moses
Deuteronomy 32:41BSB·traditional attribution

when I sharpen My flashing sword, and My hand grasps it in judgment, I will take vengeance on My adversaries and repay those who hate Me.

John Calvin Reformed @genevareformer

41 If I whet my glittering sword. The conditional particle does not leave the matter doubtful, or in suspense, but must be resolved into an adverb of time; as though He had said, As soon as He should take up arms, the destruction of the enemies would be certain; not indeed that God wants arms for the overthrow of His enemies; just as when He...

Matthew Henry Presbyterian @wholebiblehenry

This conclusion of the song speaks three things: I. Glory to God, Deu 32:39. "See now upon the whole matter, that I, even I, am he. Learn this from the destruction of idolaters, and the inability of their idols to help them." The great God here demands the glory, 1. Of a self-existence: I, even I, am he.

Commenting on Deuteronomy 32:39-43

John Gill Reformed Baptist @doctorgill

I will make mine arrows drunk with blood,.... Signifying, that by various judgments he would bring upon them, which, like arrows, would come suddenly, fly swiftly, and pierce deeply, there would be a prodigious effusion of blood like that in Rev 14:20; so that these arrows, which cause it, being plunged and soaked, and covered in it, may be said to be inebriated with it...