15:1 A gentle response turns away anger,
but a harsh word stirs up wrath.
15:2 The tongue of the wise treats knowledge correctly,
but the mouth of the fool spouts out folly.
15:3 The eyes of the LORD are in every place,
keeping watch on those who are evil and those who are good.
15:4 Speech that heals is like a life-giving tree,
but a perverse tongue breaks the spirit.
15:5 A fool rejects his father’s discipline,
but whoever heeds reproof shows good sense.
15:6 In the house of the righteous is abundant wealth,
but the income of the wicked brings trouble.
15:7 The lips of the wise spread knowledge,
but not so the heart of fools.
15:8 The LORD abhors the sacrifices of the wicked,
but the prayer of the upright pleases him.
15:9 The LORD abhors the way of the wicked,
but he loves those who pursue righteousness.
15:10 Severe discipline is for the one who abandons the way;
the one who hates reproof will die.
15:11 Death and Destruction are before the LORD—
how much more the hearts of humans!
15:12 The scorner does not love one who corrects him;
he will not go to the wise.
15:13 A joyful heart makes the face cheerful,
but by a painful heart the spirit is broken.
15:14 The discerning heart seeks knowledge,
but the mouth of fools feeds on folly.

The mouth of fools feeds on folly – Note the contrast: the discerning heart makes an active search for knowledge, whereas the fool merely spouts the foolishness he has been nibbling on.

What does it mean to ‘feed on folly’?  It means, among other things, to make a diet of trivia, gossip, and uninformed opinion.  It means to allow one’s critical faculties to fall asleep, and to treat any fable or hear-say tale or quack opinion as if it were gospel truth.  It means to rely on the evidence of a ‘sample of one’, while at the same time being impatient with careful reasoning and sound evidence.

15:15 All the days of the afflicted are bad,
but one with a cheerful heart has a continual feast.
15:16 Better is little with the fear of the LORD
than great wealth and turmoil with it.
15:17 Better a meal of vegetables where there is love
than a fattened ox where there is hatred.
15:18 A quick-tempered person stirs up dissension,
but one who is slow to anger calms a quarrel.
15:19 The way of the sluggard is like a hedge of thorns,
but the path of the upright is like a highway.
15:20 A wise child brings joy to his father,
but a foolish person despises his mother.
15:21 Folly is a joy to one who lacks sense,
but one who has understanding follows an upright course.
15:22 Plans fail when there is no counsel,
but with abundant advisers they are established.
15:23 A person has joy in giving an appropriate answer,
and a word at the right time—how good it is!
15:24 The path of life is upward for the wise person,
to keep him from going downward to Sheol.
15:25 The LORD tears down the house of the proud,
but he maintains the boundaries of the widow.

v25 As usual, it is important to appreciate the nature of proverbial truth.  ‘We know both from our own experience and from the witness of the Scriptures that there are indeed proud people whose houses are still standing and that there are widows who have been abused by greedy creditors or by fraud (cf. Mark 12:40; Job 24:2–3; et al.). So what does the proverb mean if it does not intend to convey the impression that the Lord is actually a house smasher or boundary guard? It means that God opposes the proud and is on the side of the needy (“widows,” “the fatherless,” and “foreigners” are terms that stand for all dependent people; cf. Deut 14:29; 16:11; 26:12, 13; et al.). When this proverb is compared with other moments in Scripture (Proverbs 23:10–11 and Luke 1:52–53), its meaning becomes much clearer. It is a miniature parable designed by the Holy Spirit to point beyond the “house” and the “widow” to the general principle that God will eventually right this world’s wrongs, abasing the arrogant and compensating those who have suffered for the sake of righteousness (cf. Matt 5:3–4). (Fee & Stuart, How To Read The Bible For All Its Worth)

15:26 The LORD abhors the plans of the wicked,
but pleasant words are pure.
15:27 The one who is greedy for gain troubles his household,
but whoever hates bribes will live.
15:28 The heart of the righteous considers how to answer,
but the mouth of the wicked pours out evil things.
15:29 The LORD is far from the wicked,
but he hears the prayer of the righteous.
15:30 A bright look brings joy to the heart,
and good news gives health to the body.
15:31 The person who hears the reproof that leads to life
is at home among the wise.
15:32 The one who refuses correction despises himself,
but whoever hears reproof acquires understanding.
15:33 The fear of the LORD provides wise instruction,
and before honor comes humility.