I. We have here a twofold declaration of God's great purpose in all His self-revelation, and especially in the Gospel of His Son. Our first text may be translated as a joyful exclamation; our second is an invocation or a command. The one then expresses the purpose which God secures by His gift of the law, the other the purpose which He summons us to fulfil by the tribute of our hearts and songs man's happiness and God's glory. (1) His purpose is man's blessedness. That is but another way of saying that God is love. His purpose is not blessedness anyhow, but one which will not and cannot be given by God to those who walk in the way of sinners. His love desires that we should be holy and followers of God as dear children, and the blessedness which it bestows comes from pardon and growing fellowship with Him. It can no more fall on rebellious hearts than the pure crystals of the snow can lie and sparkle on the hot black cone of a volcano. (2) God seeks our praise. "The glory of God" is the end of all the Divine actions. His glory is sought by Him in the manifestation of His loving heart, mirrored in our illuminated and gladdened heart. First He showers down blessings, then looks for the revenue of praise.
II. We may also take this passage as giving us a twofold expression of the actual effects of God's revelation, especially in the Gospel, even here upon earth. (1) God does actually, though not completely, make men blessed here. With all its sorrows and pains, the life of a Christian is a happy life, and the joy of the Lord remains with His servants. (2) So, too, God's gift produces man's praise. He requires from us nothing but our thankful recognition and reception of His benefit. The echo of love which gives and forgives is love which accepts and thanks.
III. We have also a twofold prophecy of the perfection of heaven. (1) It is the perfection of man's blessedness. The end will crown the work. (2) It is the perfection of God's praise. Our second text opens to us the gates of the heavenly temple, and shows us there the saintly ranks and angel companies gathered in the city whose walls are salvation, and its gates praise.
A. Maclaren, Sermons Preached in Manchester,3rd series, p. 225.
I. This law, which we have to learn, and by keeping of which we shall be blessed, is nothing else than God's will. If you wish to learn the law of the Lord, keep your soul pious, pure, reverent, and earnest; for it is only the pure in heart who shall see God, and only those who do God's will as far as they know it who will know concerning any doctrine whether it be true or false, in one word whether it be of God.
II. This law is the law of the Lord. You cannot have a law without a Lawgiver who makes the law, and also without a Judge who enforces the law; and the Lawgiver and the Judge of the law is the Lord Himself, our Lord Jesus Christ.
III. Christ the Lord rules, and knows that He rules; whether we know it or not, Christ's law still hangs over our head, ready to lead us to light, and life, and peace, and wealth; or ready to fall on us and grind us to powder, whether we choose to look up and see it or not. The Lord liveth, though we may be too dead to feel Him. The Lord sees us, though we may be too blind to see Him.
C. Kingsley, Westminster Sermons,p. no.
References: Psalms 1:2. Preacher's Monthly,vol. iii., p. 359; Ibid.,vol. i., p. 350; E. C. Wickham, Wellington College Sermons,p. 209; M. G. Pearse, Some Aspects of the Blessed Life,Philippians 1:17.