By the waters of Babylon (Psalm 139)

A lament for the destruction of Jerusalem worked its way into the psalms.  It takes the view of remembering Zion with longing.  

It is clearly written at a time before the Jews acclimated to Babylon.  It even seeks vengeance against the Babylonians and the very last verse wishes that someone repay the Babylonians by smashing their infants against rocks.

This is a harsh but understandable position given then they were just defeated by the Babylonians and carried off into exile.  The Babylonians may have even smashed the babies of the Jews against rocks and the psalmist longs for the same favor in return.

That said, it contrasts with Lamentations which recognizes that the Israelites brought the destruction of Jerusalem on themselves.  Here, in psalm 139, it reflects sorrow and perhaps bitterness and lacks recognition that they were in part to blame.