Charles H. Spurgeon on Psalms 57:9

The people —the nations. The Hebrew church was neither called nor qualified to be a missionary society, but it never ceased to desire and hope for the conversion of the nations. This is seen in those passages in which the psalmists betray a consciousness that they shall one day have all the world for auditors. How boldly does David exclaim, I will sing unto thee among the nations. In the same spirit, a later psalmist summons the church to lift up her voice, so that all the nations may hear her recital of the Lord's mighty acts: O give thanks unto the Lord; call upon his name: make known his deeds among the people. Ps 105:1. The full import of this class of texts is often hidden from the English reader by the circumstance that our translators have hardly ever used the word people in its plural form. Twice in the Revelation they venture to write peoples; everywhere else the singular form has to do duty for both numbers; so that in not a few passages the sense is greatly obscured to those who have no access either to the original or to other versions. In the Psalms, in particular, the mention of the Gentiles is more frequent than the English reader is made aware of. It is to be observed, moreover, that in addition to this strain of indirect prediction, the conversion of the world is articulately celebrated in many glorious Psalms. Indeed, so numerous are these, and so generally distributed over the centuries between David and Ezra, that it would seem that at no time during the long history of inspired Psalmody, did the Spirit cease to indite new songs in which the children of Zion might give utterance to their world embracing hopes. William Binnie, D.D., in "The Psalms: their History, Teachings, and Use, "1870.

Verses 10-11. A hard and ungrateful heart beholds even in prosperity only isolated drops of divine grace; but a grateful one like David's, though chased by persecutors, and striking the harp in the gloom of a cave, looks upon the mercy and faithfulness of God as a mighty ocean, waving and heaving from the earth to the clouds, and from the clouds to the earth again. Agustus F. Tholuck.