By the waters of Babylon

we wept when we remembered Sion. Psalm 136 (137)

In the third week, reflecting on our exile from God due to our sin, at Orthros, we chant this psalm before we chant the Evlogetaria which proclaims Christ's trampling down death by death. This is how it is chanted in the churches which use the Typicon of the Great Church of Christ. It is an absolute favorite of mine.