To the chief Musician, A Psalm of David. The king shall {a} joy in thy strength, O LORD; and in thy salvation how greatly shall he rejoice!

(a) When he will overcome his enemies, and so be assured of his calling.Psalm 21:1 Parallel Commentaries

Fourteenth Day for the Church of the Future
WHAT TO PRAY.--For the Church of the Future "That the children might not be as their fathers, a generation that set not their heart aright, and whose spirit was not steadfast with God."--PS. lxxviii. 8. "I will pour My Spirit upon thy seed, and My blessing upon thy offspring."--ISA. xliv. 3. Pray for the rising generation, who are to come after us. Think of the young men and young women and children of this age, and pray for all the agencies at work among them; that in association and societies …
Andrew Murray—The Ministry of Intercession

Of Deeper Matters, and God's Hidden Judgments which are not to be Inquired Into
"My Son, beware thou dispute not of high matters and of the hidden judgments of God; why this man is thus left, and that man is taken into so great favour; why also this man is so greatly afflicted, and that so highly exalted. These things pass all man's power of judging, neither may any reasoning or disputation have power to search out the divine judgments. When therefore the enemy suggesteth these things to thee, or when any curious people ask such questions, answer with that word of the Prophet, …
Thomas A Kempis—Imitation of Christ

Psalms
The piety of the Old Testament Church is reflected with more clearness and variety in the Psalter than in any other book of the Old Testament. It constitutes the response of the Church to the divine demands of prophecy, and, in a less degree, of law; or, rather, it expresses those emotions and aspirations of the universal heart which lie deeper than any formal demand. It is the speech of the soul face to face with God. Its words are as simple and unaffected as human words can be, for it is the genius …
John Edgar McFadyen—Introduction to the Old Testament