Psalms 137:1

the rivers of Babylon Not only the Euphrates and its tributaries, such as the Chebar (Ezekiel 1:1; Ezekiel 3:15), but the numerous canals with which the country was intersected. Babylonia was characteristically a land of streams, as Palestine was a land of hills; it was the feature of the country which would impress itself upon the mind of the exiles. Cp. Jeremiah 51:13. They may have resorted to the banks of the rivers and canals to mourn; partly for the sake of the shade of the trees which grew there, partly because such places were suitable to melancholy meditation.

It is hardly likely that there is any reference to places of prayer chosen near water for the sake of ceremonial lustrations (Acts 16:13).

sat down As mourners. Cp. Isaiah 47:1; Isaiah 47:5.

Zion The name is chosen specially to suggest the sacred memories of the city.