Ecclesiastes 12:13

The great enquiry which Solomon prosecutes in this book is, What is that good which the sons of men should do? Ecc 2:3. What is the true way to true happiness, the certain means to attain our great end? He had in vain sought it among those things which most men are eager in pursuit of, but here, at length, he has found it, by the help of that discovery which God anciently made to man (Job 28:28), that serious godliness is the only way to true happiness: Let us hear the conclusion of the whole matter, the return entered upon the writ of enquiry, the result of this diligent search; you shall have all I have been driving at in two words. He does not say, Do you hear it, but Let us hear it; for preachers must themselves be hearers of that word which they preach to others, must hear it as from God; those are teachers by the halves who teach others and not themselves, Rom 2:21. Every word of God is pure and precious, but some words are worthy of more special remark, as this; the Masorites begin it with a capital letter, as that Deu 6:4. Solomon himself puts a nota bene before it, demanding attention in these words, Let us hear the conclusion of the whole matter. Observe here, I. The summary of religion. Setting aside all matters of doubtful disputation, to be religious is to fear God and keep his commandments. 1.

— Matthew Henry's Concise Commentary (public domain)

The grand inference of the whole book. Fear God--The antidote to following creature idols, and "vanities," whether self-righteousness (Ecc 7:16, Ecc 7:18), or wicked oppression and other evils (Ecc 8:12-13), or mad mirth (Ecc 2:2; Ecc 7:2-5), or self-mortifying avarice (Ecc 8:13, Ecc 8:17), or youth spent without God (Ecc 11:9; Ecc 12:1). this is the whole duty of man--literally, "this is the whole man," the full ideal of man, as originally contemplated, realized wholly by Jesus Christ alone; and, through Him, by saints now in part, hereafter perfectly (Jo1 3:22-24; Rev 22:14).

— Jamieson-Fausset-Brown Commentary (public domain)