Psalm 1:1 (BSB)

Blessed is the man who does not walk in the counsel of the wicked, or set foot on the path of sinners, or sit in the seat of mockers.

From Psalms 1. Also in the ESV.

Commentary on Psalm 1:1

• John Calvin (Reformed), Calvin's Commentaries on Psalm 1:1-6: Commentary upon the book of Psalms PSALM 1. He who collected the Psalms into one volume, whether Ezra or some other person, appears to have placed this Psalm at the beginning, by way of preface, in which he inculcates upon all the godly the duty of meditating upon the law of God.
• C.H. Spurgeon (Reformed Baptist), The Treasury of David on Psalm 1:1: Blessed— see how this Book of Psalms opens with a benediction, even as did the famous Sermon of our Lord upon the Mount! The word translated "blessed" is a very expressive one. The original word is plural, and it is a controverted matter whether it is an adjective or a substantive.
• Matthew Henry (Presbyterian), Matthew Henry's Complete Commentary on Psalm 1:1-3: The psalmist begins with the character and condition of a godly man, that those may first take the comfort of that to whom it belongs. Here is, I. A description of the godly man's spirit and way, by which we are to try ourselves.
• John Gill (Reformed Baptist), Exposition of the Old and New Testaments on Psalm 1:1: Blessed is the man,.... This psalm begins in like manner as Christ's sermon on the mount, Mat 5:3; setting forth the praises and expressing the happiness of the man who is described in this verse and Psa 1:2. The words may be rendered, "O, the blessednesses of the man", or "of this man" (l); he is doubly blessed, a thrice happy and blessed man; blessed...