The chorus isn't based on an old saying, but actual scripture, which inspired much of the song. It's derived from Psalm 137:
1By the rivers of Babylon,
There we sat down and wept,
When we remembered Zion.
2Upon the willows in the midst of it
We hung our harps.
3For there our captors demanded of us songs,
And our tormentors mirth, saying,
"Sing us one of the songs of Zion."
4How can we sing the LORD'S song
In a foreign land?
5If I forget you, O Jerusalem,
May my right hand forget her skill.
6May my tongue cling to the roof of my mouth
If I do not remember you,
If I do not exalt Jerusalem
Above my chief joy.
7Remember, O LORD, against the sons of Edom
The day of Jerusalem,
Who said, "Raze it, raze it
To its very foundation."
8O daughter of Babylon, you devastated one,
How blessed will be the one who repays you
With the recompense with which you have repaid us.
9How blessed will be the one who seizes and dashes your little ones
Against the rock.
The chorus isn't based on an old saying, but actual scripture, which inspired much of the song. It's derived from Psalm 137:
1By the rivers of Babylon, There we sat down and wept, When we remembered Zion. 2Upon the willows in the midst of it We hung our harps. 3For there our captors demanded of us songs, And our tormentors mirth, saying, "Sing us one of the songs of Zion." 4How can we sing the LORD'S song In a foreign land? 5If I forget you, O Jerusalem, May my right hand forget her skill. 6May my tongue cling to the roof of my mouth If I do not remember you, If I do not exalt Jerusalem Above my chief joy. 7Remember, O LORD, against the sons of Edom The day of Jerusalem, Who said, "Raze it, raze it To its very foundation." 8O daughter of Babylon, you devastated one, How blessed will be the one who repays you With the recompense with which you have repaid us. 9How blessed will be the one who seizes and dashes your little ones Against the rock.