By the rivers of Babylon— there we sat down and there we wept when we remembered Zion.

On the willows there we hung up our harps.

For there our captors asked us for songs, and our tormentors asked for mirth, saying, "Sing us one of the songs of Zion!"

How could we sing the Lord's song in a foreign land?

If I forget you, O Jerusalem, let my right hand wither!

Let my tongue cling to the roof of my mouth, if I do not remember you, if I do not set Jerusalem above my highest joy.

The Jews who are in exile in Babylon are being mocked.  Their captors are asking them to play the songs of Zion, literally the "songs of the Lord" used for temple worship.  It is as if they are saying "where is your temple, where is your Lord?"

We Christians have much to learn from our Jewish brethren of generations past.  Christians are also "aliens and exiles" in this world (1 Peter 2.11).  We must never forget that our true home is in heaven, lest we set up a permanent home here in exile.  In order that we not forget, Saint Peter said that we "should remember the words spoken in the past by the holy prophets, and the commandment of the Lord and Savior spoken through your apostles." (2 Peter 3.2)  In the very next line he warns us that we too may face the same scoffing that the Jews of the Diaspora encountered: "In the last days scoffers will come, scoffing and indulging their own lusts and saying, "Where is the promise of his coming?  For ever since our ancestors died, all things continue as they were from the beginning of creation!" (2 Peter 3.3-4)  We must never believe their lies.  The purpose of God's patience is that all come to repentance. (2 Peter 3.9)

While we are waiting for the glorious revelation of all God's chosen ones here in this exile, "May we never forget you, heavenly Jerusalem, may we always remember you, may we set you above our highest joy." (Psalm 137.5-6)