Albert Barnes Commentary Psalms 126:2

"Then was our mouth filled with laughter, And our tongue with singing: Then said they among the nations, Jehovah hath done great things for them." — Psalms 126:2 (ASV)

Then was our mouth filled with laughter — Then we were happy; completely happy. See Job 8:21.

And our tongue with singing — We expressed our joy in songs—the natural expression of joy. Young converts—those “turned” from sin to God—sing. Their feelings find expression in the songs of Zion. This is natural; this is proper; this will occur when sinners are converted. An assembly of young converts is always a happy assembly; a place where there is a “revival” of religion is always a happy place—full of songs and singing.

Then said they among the heathen — The nations; the people among whom they lived.

The Lord hath done great things for them — In causing their return to their own land; in ordering the arrangements for it; in bringing their captivity to an end; and in securing such intervention from the civil rulers as to facilitate their return. This would indicate that the surrounding people did not have an unfriendly feeling toward them, but that they pitied them in exile, and were disposed to acknowledge the hand of God in what was done. Their deliverance, in the circumstances, was so evidently the work of God. This will agree well with the account of the return of the exiles from Babylon, and with all that had been done for them by Cyrus. Compare to Ezra 1:1-4.