Synopsis of the Books of the Bible, by John Nelson Darby, [1857-62], at sacred-texts.com
Psalm 108 is a psalm of a peculiar character, being composed of the ends of two others, the earlier and the latter parts of which, the cry of deep distress, and the answer to the cry in faith and hope, have been here put together. The former part of this, the end of Psalm 57, expresses the fixed assurance of the godly heart, who can now give praise and will praise among the peoples (ammin), united now in relation with Israel and in the various races of people. But all the results of God's favor are not yet produced, and the same faith, taking up Psalm 60, leaving out the cry of distress, celebrates the going out of Him whose mercy is above the heavens, to bring into subjection all those who are yet in possession of different parts of the territory of Israel.
It may be remarked here that the general character of this, as indeed of the previous book, as far as regards the position of Israel, is that of the people being restored by God to the land and delivered, but not free yet from attack, nor in possession of all the promised land; so that there is thanksgiving and praise, for God has interfered, and the state of Israel is changed; but there remains the need of help and securing against enemies yet undestroyed, and the full blessing of God in peace. A very few psalms at the end are of unmingled praise, and only praise called for. This state of deliverance, and yet full security waited for, is expressed at the end of Psalm 107; as to final deliverance, the fact only is stated.
The connection of the two parts of this psalm is not without interest. The first part praises Jehovah for what He is as known to the heart in faith; but God in contrast with man. His mercy is great above the heavens and His truth reaches to the clouds, mercy being as ever first as the root of all. The second part begins with looking for Jehovah to rise up as God above the heavens and His glory above all the earth. He is to take His place and vindicate His name as God, that His beloved may be delivered. Verse 7 (Psa 108:7) brings out the answer of God, taking up in detail all Israel's rights as His. Thus Jehovah has war with the nations possessing their land, but it is in Israel, and through God they will do valiantly. Hence here it is God, not Jehovah, because it is not the covenant relation, but what He, who is so, is in contrast with man whose help is vain.