Adam Clarke on Proverbs 3:12

Whom the Lord loveth - To encourage thee to bear correction, know that it is a proof of God's love to thee; and thereby he shows that he treats thee as a father does his son, even that one to whom he bears the fondest affection.

The last clause the Septuagint translate μαστιγοι δε παντα υἱον ὁν παραδεχεται, "and chasteneth every son whom he receiveth;" and the apostle, Heb 12:6, quotes this literatim. Both clauses certainly amount to the same sense. Every son whom he receiveth, and the son in whom he delighteth, have very little difference of meaning.