Solomon
Proverbs 31:1ESV·traditional attribution

The words of King Lemuel. An oracle that his mother taught him:

Matthew Henry Presbyterian @wholebiblehenry

Most interpreters are of opinion that Lemuel is Solomon; the name signifies one that is for God, or devoted to God; and so it agrees well enough with that honourable name which, by divine appointment, was given to Solomon (Sa2 12:25), Jedediah - beloved of the Lord.

Commenting on Proverbs 31:1-9

John Gill Reformed Baptist @doctorgill

The words of King Lemuel,.... Not what were spoken by him, but what were spoken to him; or declaring what his mother said, as what follows shows; of this king we have no account elsewhere under this name. Grotius thinks that King Hezekiah, whose mother Abijah, the daughter of Zechariah, whom he supposes to be a wise man, from whom she had learned much, instructed...

Geneva Bible Notes Reformed @genevanotes

The words of king Lemuel, the prophecy that his mother taught him. (a) That is, of Solomon who was called Lemuel, that is, of God, because God had ordained him to be king over Israel. (b) The doctrine which his mother Bathsheba taught him.