Psalm 136: By the Rivers of Babylon

Psalm 136.
By the waters of Babylon, there we sat down and we wept when we remembered Sion. Upon the willows in the midst thereof did we hang our instruments. For there, they that had taken us captive asked us for words of song. And they that had led us away asked us for a hymn, saying: Sing us one of the songs of Sion. How shall we sing the Lord's song in a strange land? If I forget thee, O Jerusalem, let my right hand be forgotten. Let my tongue cleave to my throat, if I remember thee not, If I set not Jerusalem above all other, as at the head of my joy. Remember, O Lord, the sons of Edom, in the day of Jerusalem, Who said: Lay waste, lay waste to her, even to the foundations thereof. O daughter of Babylon, thou wretched one, blessed shall he be who shall reward thee wherewith thou hast rewarded us. Blessed shall he be who shall seize and dash thine infants against the rock.