Albert Barnes' Bible Commentary
Psalms 108 - Introduction
This psalm is ascribed to David, and there is no reason to doubt the correctness of the title in this respect. The psalm is not an original composition, but is made up, with slight alterations, of parts of two other psalms, Psalms 57:7; Psalms 60:5.
When the psalm was so arranged, or why the parts of two former psalms were thus brought together to form a new composition, it is impossible now to determine. It “may” have been for a mere purpose of art; or it may, more probably, have occurred when the two parts of psalms already in use might be so combined as to be adapted to some new event. It may have been, also, that what had been expressed “on two different occasions” might now be fulfilled or accomplished “on some one occasion,” and that thoughts which had been expressed separately before might now be unitedly uttered in praise. Rosenmuller supposes that the psalm in its present form was arranged on the return from the captivity at Babylon, and that the parts of the two separate psalms were found to be suitable for a national song at that time, and were therefore thus brought together. This supposition would have much probability if the psalm were not ascribed to David; and perhaps this fact need not be an insuperable objection - since, if the two psalms from which this is compiled were the work of David, the author of the arrangement might without impropriety attribute the composition itself to David.
There are some slight variations in the psalm, as here arranged, from the original psalms; but why these were made cannot now be determined. Substantially all that will be necessary in the exposition of the psalm will be to notice these variations.