Psalms - Chapter 108
Haven't We Seen This Somewhere Before?
Psalm 108 is unusual in that it basically mirrors ideas David has already expressed in other Psalms. The first half of this Psalm is essentially the end of Psalm 57, while the second half is like Psalm 60.
Like Psalm 57:
David's heart is true, so he praises G-d with song, arising even before dawn to do so. He thanks G-d in full view of the nations of the world because His kindness and truth know no bounds. David hopes that G-d will soon reveal His glory over all the people in the world, through Israel's redemption.
Like Psalm 60:
G-d has promised Israel dominion and an end to border disputes. He owns the whole world, from Gilad to Menashe; both Ephraim (the northern kingdom of Israel - the "Ten Tribes") and Judah. He owns Edom, Moav and the land of the Philistines like a person might own physical property, and He will treat each nation as they have earned.
David asks who will help him conquer Edom? He prays that G-d will continue to go forth with his army into battle, even though He sometimes lets Israel lose. David asks for continuing support from G-d against Israel's enemies because human help is powerless. With G-d's help, the nation is unified and unbeatable.