Solomon
Ecclesiastes 12:9ESV·traditional attribution

Besides being wise, the Preacher also taught the people knowledge, weighing and studying and arranging many proverbs with great care.

Matthew Henry Presbyterian @wholebiblehenry

Solomon is here drawing towards a close, and is loth to part till he has gained his point, and prevailed with his hearers, with his readers, to seek for that satisfaction in God only and in their duty to him which they can never find in the creature. I. He repeats his text (Ecc 12:8), 1.

Commenting on Ecclesiastes 12:8-12

John Gill Reformed Baptist @doctorgill

And moreover,.... Or "besides" (z) what has been said; or "as to what remains" (a); or "but what is better", or "more excellent" (b), is to "hear the conclusion of the whole matter", the sum and substance of the whole book in a few words, Ecc 12:13; to which Ecc 12:9; are a preface; and in which the wise man recommends the reading of this...

Jamieson-Fausset-Brown Reformed @jfbcommentary

gave good heed--literally, "he weighed." The "teaching the people" seems to have been oral; the "proverbs," in writing. There must then have been auditories assembled to hear the inspired wisdom of the Preacher. See the explanation of Koheleth in the Introduction, and chapter 1 (Kg1 4:34). that which is written, &c.--rather, (he sought) "to write down uprightly (or, 'aright') words of truth" [HOLDEN and WEISS].