Blessed is the man whom thou chastenest, O Lord - “Happy the man;” or “Oh the blessedness of the man.” See the notes at Psalms 1:1. The word here rendered “chastenest” does not mean to chasten in the sense of afflicting or punishing. It means here to instruct; to warn; to admonish; to exhort. So the word is employed in Proverbs 9:7; Job 4:3; Psalms 16:7. The meaning here is, that the man is blessed or happy whom God so “instructs, warns, or teaches,” that he understands the principles of the divine administration. Such a man will see reasons for confidence in him in trouble, and for calmness of mind until punishment is brought upon his enemies.
And teachest him out of thy law - Causest him, from thy word, to understand the great principles of thy government.