Charles H. Spurgeon on Psalms 137:4

The Lord's song —in a strange land. It was the contrast, it was the incongruity which perplexed them. The captives in Babylon —that huge, unwieldy city, with its temple of the Chaldean Bel towering aloft on its eight stupendous stories to the height of a furlong into the sky —the Israelite exiles, bidden there to an idolatrous feast, that they might make sport for the company by singing to them one of the far famed Hebrew melodies, for the gratification of curiosity or the amusement of the ear —how could it be done? The Lord's song —one of those inspired compositions of Moses or David, in which the saintly soul of the king or the prophet poured itself forth in lowliest, loftiest adoration, before the one Divine Creator, Redeemer, and Sanctifier —how could it be sung, they ask, in a scene so incongruous? The words would languish upon the tongue, the notes would refuse to sound upon the disused harp. Such Psalmody requires its accompaniment and its adaptation —if not actually in the Temple courts of Zion, yet at least in the balmy gales of Palestine and the believing atmosphere of Israel. —C. J. Vaughan, in "The Family Prayer and Sermon Book."