Sound wisdom - "Soundness," an idea which passes on into that of health and safety. Compare "sound doctrine" in 1-Timothy 1:10; 2-Timothy 4:3.

He layeth up sound wisdom - תושיה tushiyah. We have met with this word in Job; see Job 5:12; Job 6:13; Job 11:6; Job 12:16. See especially the note on Job 11:6 (note), where the different acceptations of the word are given.
Coverdale translates, "He preserveth the welfare of the righteous." It is difficult to find, in any language, a term proper to express the original meaning of the word; its seems to mean generally the essence or substance of a thing, The thing itself - that which is chief of its kind. He layeth up What Is Essential for the righteous.

He layeth up sound wisdom for the righteous,.... In order to give it to them that seek for it; which is another encouragement to search after it. By "sound wisdom" may be meant, not the law, as Kimchi and Ben Melech; so called, because it endures for ever, when all beings are defective and come to nothing; but the Gospel, which is sound doctrine, pure and not corrupt; true and real wisdom, in opposition to that which has only the show of wisdom, and is science falsely so called; and this was hid in God, in Christ, and laid up as a treasure in the sacred Scriptures: or else the true grace of God, in distinction from that which is counterfeit; and is that goodness of his, which he has laid up in his heart, and in the covenant of his grace; and the fulness of grace which he has laid up in Christ for them Psalm 31:19; or eternal glory and happiness. The word here used signifies "essence", "substance" (o); that which really is, and is solid and substantial; and such are the glories of the other world the crown of righteousness, the hope laid up in heaven, and the inheritance reserved there, Colossians 1:5. These are real things, though invisible, and are rich and valuable; and have substance and solidity in them, in opposition to earthly riches, which are a vain show, and are things that are not, and at best temporal and perishing; but these are an enduring substance, Proverbs 8:21. The Septuagint render it by "salvation", and the Targum by a word which signifies "glory" and "honour"; all which may well be understood of eternal life which is laid up and reserved "for the righteous": not for such who are only so in show and imagination, but for those who are really and truly so; not for those who are legally, but evangelically righteous; or not for such that seek righteousness by the law, but by faith in Christ; for such who are made righteous by the righteousness of Christ imputed to them, and by faith receive it, and lay hold on it as their righteousness; and in consequence of this live soberly and righteously: for these only eternal life is prepared; they only have a right unto it, and a meetness for it, and shall enjoy it;
he is a buckler to them that walk uprightly; who are sincere in their deportment before God and men; who walk according to the rule of the divine word; who walk by faith on Christ, and walk on in him as they have received him; and go on living by faith on his righteousness, which is walking in his uprightness, till they come to be with him for ever in heaven. To these the Lord is a "buckler" or shield; he covers them with the "shield of faith", his own Son, his blood righteousness, and sacrifice; which faith lays hold on and uses as a shield against Satan's fiery darts; and gives them "the shield of salvation" which secures them from sin and wrath and every enemy; and encompasses them about with his "favour", as a "shield", which is immutable and invariable; and keeps them by his power through faith unto salvation, Ephesians 6:16; with this compare Genesis 15:1, Psalm 3:3. Some (p) read these words by way of apposition, and understand them of sound wisdom; that that is a buckler or shield to the persons here described; see Ecclesiastes 7:12.
(o) "essentiam", Pagninus, Montanus, Tigurine version, Mercerus, Gejerus; "quicquid revera est", Junius & Tremellius; "solidam firmamque substantiam", Baynus; "solidum, vel solidam rem", Schultens. (p) So Mercerus, Piscator, Schultens. Gussetius chooses to take the word for a verb, and renders it, "he delivers it"; that is, sound wisdom to them that walk uprightly; Ebr. Comment. p. 454.

sound wisdom--literally, "substance," opposed to what is fictitious. According to the context, this may be assistance, as here corresponding with
buckler--or safety, or wisdom, which procures it (compare Proverbs 3:21; Proverbs 8:14; Proverbs 18:1; Job 6:13; Job 12:13).
layeth up--provides, ever ready.