Psalms 147:2

The Lord doth build up Jerusalem - He builds up the walls; he restores the city; he has caused the temple to be reconstructed. This language would be applicable to a return from the captivity. There may be an allusion here to the language in Psalms 102:16 : “When the Lord shall build up Zion, he shall appear in his glory.” See the notes at that passage. What is there spoken of as what would be in the future is here spoken of as accomplished, and as a ground of praise.

He gathereth together the outcasts of Israel - Those who have been exiled from their native land, and who have been scattered as outcasts in a foreign country. This is appropriate language to use on the supposition that the psalm was composed after the return from the exile, for it is in such language that that return was predicted by the prophets. Isaiah 11:12 : “and he shall assemble the outcasts of Israel, and gather together the dispersed of Judah,” etc. Isaiah 56:8 : “the Lord God which gathereth the outcasts of Israel,” etc.