Psalm 136 

In the Orthodox Church, this Psalm is sung during Lent to remind us to keep fresh the knowledge of what we have fallen from, how alien we are to the place we now live, and what we hope to regain.

Saint Augustine wrote a sermon on Psalm 136, find it on Fr. Silouan’s site at https://silouanthompson.net/2013/02/saint-augustine-on-psalm-136/