He that spareth his rod hateth his son - That is, if he hated him, he could not do him a greater disservice than not to correct him when his obstinacy or disobedience requires it. We have met with this subject already, and it is a favourite with Solomon. See Psalm 34:10 (note) and Psalm 37:3 (note).
The Revelation. Mr. Holden makes some sensible observations on this passage: "By the neglect of early correction the desires (passions) obtain ascendancy; the temper becomes irascible, peevish, querulous. Pride is nourished, humility destroyed, and by the habit of indulgence the mind is incapacitated to bear with firmness and equanimity the cares and sorrows, the checks and disappointments, which flesh is heir to."

He that spareth his rod hateth his son,.... Who withholds or withdraws his rod of correction, which is in his hand, which he has power to use, and ought to exercise at proper times; he, instead of loving his son, may be said to hate him; for such fond love is no better than hatred; and, if he really hated him, he could scarcely do a more ill thing by him than not to correct him for a fault; which was the sin of good old Eli, and both he and his sons suffered for it;
but he that loveth him; that has a true love for his son, and a hearty concern for his welfare and future good; he will regulate his affections by his judgment, and not give way to a fond passion, to the prejudice of his child: but he
chasteneth him betimes, or "in the morning" (x); in the morning of his infancy, before vicious habits are contracted, or he is accustomed to sinning, and hardened in it; or as soon as a crime is perpetrated, before it is forgot or repeated: or every morning, as Jarchi and Aben Ezra; that is, continually, as often as it is necessary, or as faults are committed.
(x) "mane castigat eum", Munster; "matutinat ei disciplinam", Michaelis.

He acts as if he hated his child, who, by false indulgence, permits sinful habits to gather strength, which will bring sorrow here, and misery hereafter.

spareth--or, "withholds."
rod--of correction.
hateth--or, acts as if he hated him (compare Proverbs 3:12; Proverbs 8:36).
chasteneth . . . betimes--or, "diligently seeks for him all useful discipline."

24 He that spareth his rod hateth his son,
And he who loveth him visits him early with correction.
The paedagogic rule of God, Proverbs 3:12, avails also for men, Proverbs 23:13., Proverbs 29:15. The rod represents here the means of punishment, the patria potestas. He who spareth or avoideth this, and who does this even from love, has yet no true right love for his son; he who loveth him correcteth him early. With ἐπιμελῶς παιδεύει of the lxx (cf. Sir. 30:1, ἐνδελεχήσει μάστιγας) the thought is in general indicated, but the expression is not explained. Many erroneously regard the suffix of שׁחרו as referring to the object immediately following (de Dieu, Ewald, Bertheau, Zckler); Hitzig, on the contrary, rightly remarks, that in this case we should expect the words to be, after Proverbs 5:22 (cf. Exodus 2:6), את־המּוּסר. He himself, without any necessity, takes שׁחר in the sense of the Arab. skhar, compescere. Hofmann (Schriftbew. ii. 2. 402) is right in saying that "שׁחר is connected with a double accusative as elsewhere קדּם occurs; and the meaning is, that one ought much more to anticipate correction than restrain it where it is necessary." שׁחר means to go out early to anything, according to which a Greek rendering is ὀρθρίζει (Venet. ὀρθριεῖ) αὐτῷ παιδείαν: maturat ei castigationem = mature eum castigat (Fl.). שׁחר does not denote the early morning of the day (as Rashi, לבקרים), but the morning of life (as Euchel, בשׁחר ימיו). "The earlier the fruit, the better the training." A father who truly wishes well to his son keeps him betimes under strict discipline, to give him while he is yet capable of being influenced the right direction, and to allow no errors to root themselves in him; but he who is indulgent toward his child when he ought to be strict, acts as if he really wished his ruin.

Hateth his son - His fond affection, is as pernicious to him as hatred.