They shall speak of the glory of thy kingdom - Of thy reign; of the great principles of thy government and laws. They see in that reign evidence that thou art worthy of universal praise. Seeing this, it becomes to them a subject on which they talk or converse (compare Malachi 3:16) - a subject of interest to their hearts, and "out of the abundance of the heart the mouth speaks." People talk about that which interests them; those things in which they have pleasure; those which they desire to understand; those in which they see difficulties that they would wish to have solved. It is one of the characteristics of the "saints" - of the people of God - that they do talk about God and his kingdom; that the subject is to them a pleasant theme of meditation and conversation; that they have the kind of pleasure in talking about God which other people have in conversing about their farms or their merchandise, their children and friends, the news of the day, politics, literature, or science.
And talk of thy power - As put forth in the works of creation; as manifested in the dispensations of thy providence; as evinced in the conversion of sinners; as displayed in carrying thy truth around the world; as exhibited in sustaining fine sufferer, and in giving peace and support to the dying.

(f) They shall speak of the glory of thy kingdom, and talk of thy power;
(f) The praise of your glory belongs in all your creatures and though the wicked would obscure the same by their silence, yet the faithful are always mindful of the same.

They shall speak of the glory of thy kingdom,.... That is, the saints who are his special workmanship, in the celebration of his praise; and, while they are blessing him, will take particular notice, and make particular mention of his kingdom, and the glory of it; not only his kingdom of nature and providence, which ruleth over all, angels and men, good and bad; which deserves the notice of the saints, and is matter of great joy unto them, that their King reigns in the world, but also, and rather, his kingdom of grace, in which he rules by his Spirit and grace in the hearts of his people; which is not worldly, but spiritual; is not with outward observation, but lies within the heart, and makes the Lord's people all glorious within; consisting of peace, righteousness, and joy in the Holy Ghost, and is what can never be removed. The church is Christ's kingdom, in which he reigns; and all the subjects of it are kings and priests unto God: here proper laws are made and observed, and officers appointed to explain them, and see them put in execution; glorious ordinances are administered, in which Christ the King is seen in his beauty; and the glorious Gospel, which is his sceptre, is held forth, and by which he rules in the midst of his enemies. More especially this may regard the glorious kingdom of Christ in the latter day; both in his spiritual reign, in which there will be a great display of glory; as a large effusion of the Spirit; much spiritual light and knowledge; great holiness of heart and life; an abundance of peace, temporal and spiritual; great purity of Gospel doctrine, worship, and ordinances: and also in his personal reign; when he will appear glorious, and reign before his ancients gloriously, and his saints will appear with him in glory; the New Jerusalem will have the glory of God upon her; a glory there will be then both upon the bodies and souls of the saints Christ will have with him in that state:
and talk of thy power; not only as exerted in creation and providence; but of his power in working out the salvation of men; and in conquering and subduing all the spiritual enemies of his people, sin, Satan, the world, and death; in raising himself from the dead, as he will all his saints by the same power at the last day; in going forth into the Gentile world in the ministry of the word, conquering and to conquer, making it powerful and effectual to the conversion of thousands: and also of his power in heaven and in earth, given him as Mediator; and which he has exercised and does exercise on the behalf of his church, and for its protection and welfare: and especially of the more open display of it in the latter day, when he shall take to himself his great power and reign; then will his saints talk of it with great pleasure and thankfulness; see Revelation 11:15.

The declaration of God's glory is for the extension of His knowledge and perfections in the world.