Lay up - The point of the maxim is that the wise man reserves what he has to say for the right time, place, and persons (compare Matthew 7:6), as contrasted with the foolish, ever giving immediate utterance to what destroys himself and others.

Wise men lay up knowledge - They keep secret every thing that has a tendency to disturb domestic or public peace; but the foolish man blabs all out, and produces much mischief. Think much, speak little, and always think before you speak. This will promote your own peace and that of your neighbor.

Wise men lay up knowledge,.... Which they get by reading, prayer, meditation, hearing the word of God, and conversation with good men: this they lay up in their hearts, minds, and memories, that they may not forget it, and as a rich treasure they highly value it; that they may bring it forth at proper times, and on proper occasions, for the benefit of others; see Matthew 12:35; or hide (f) it; conceal it; do not boast and brag of it, as foolish men do;
but the mouth of the foolish is near destruction: who rashly and unguardedly utters things which bring swift and sudden destruction on himself and others; or terror and consternation, as the word (g) also signifies. The Vulgate Latin version is, "but the mouth of the foolish is near to confusion"; he boasts of his knowledge, betrays his ignorance, and so brings himself to shame and confusion.
(f) "abscondent", Pagninus, Montanus; "abscondunt", V. L. "occultant", Michaelis. (g) "terrorem accersit", Tigurine version; "consternatio propinqua", Cocceius; "terror", Vatablus, Michaelis.

Whatever knowledge may be useful, we must lay it up, that it may not be to seek when we want it. The wise gain this wisdom by reading, by hearing the word, by meditation, by prayer, by faith in Christ, who is made of God unto us wisdom.

lay up knowledge--that is, as treasures for good use.
mouth . . . destruction--or, "as to the mouth," &c., destruction is near; they expose themselves to evil by prating.

14 Wise men store up knowledge;
But the mouth of the fool is threatening destruction.
Ewald, Bertheau, Hitzig, Oetinger: "The mouth of the fool blunders out, and is as the sudden falling in of a house which one cannot escape from." But since מחתּה is a favourite Mishle-word to denote the effect and issue of that which is dangerous and destructive, so the sense is perhaps further to be extended: the mouth of the fool is for himself (Proverbs 13:3) and others a near, i.e., an always threatening and unexpectedly occurring calamity; unexpectedly, because suddenly he blunders out with his inconsiderate shame-bringing talk, so that such a fool's mouth is to every one a praesens periculum. As to יצפּנוּ, it is worthy of remark that in the Beduin, Arab. dfn, fut. i, signifies to be still, to be thoughtful, to be absorbed in oneself (vid., Wetstein on Job, p. 281). According to Codd. and editions, in this correct, וּפי־ is to be written instead of אויל uwpiy; vid., Baer's Torath Emeth, p. 40.

Lay up - In their minds, to be brought forth upon fit occasions. Knowledge - Whereby they may be enabled to speak both what, and when it is seasonable. But - Fools are more forward to lay out than to lay up, and for want of knowledge speak much and foolishly, whereby they frequently bring destruction upon themselves.