The Geneva Bible Translation Notes, [1599], at sacred-texts.com
(a) That is, we abode a long time, and even though the country was pleasant, yet it could not stay our tears, nor turn us from the true service of our God.
We hanged our harps upon the willows in the midst (b) thereof.
(b) That is, of that country.
For there they that carried us away captive (c) required of us a song; and they that wasted us [required of us] mirth, [saying], Sing us [one] of the songs of Zion.
(c) The Babylonians speak thus in mocking us, as though by our silence we should signify that we hoped no more in God.
(d) If I forget thee, O Jerusalem, let my right hand forget [her cunning].
(d) Even the faithful are touched by their particular griefs, yet the common sorrow of the Church is most grievous to them, and is such as they cannot but remember and lament.
If I do not remember thee, let my tongue cleave to the roof of my mouth; if I prefer not Jerusalem above my (e) chief joy.
(e) The decay of God's religion in their country was so grievous that no joy could make them glad, unless it was restored.
Remember, O LORD, the children of (f) Edom in the (g) day of Jerusalem; who said, Rase [it], rase [it, even] to the foundation thereof.
(f) As was prophesied in (Eze 25:13, Jer 49:7, Oba 1:10), showing that the Edomites who came from Esau, conspired with the Babylonians against their brethren and kinsfolk.
(g) When you visited Jerusalem.
(h) Happy [shall he be], that taketh and dasheth thy little ones against the stones.
(h) He alludes to Isaiah's prophecy in (Isa 13:16) promising good success to Cyrus and Darius, whom ambition moved to fight against Babylon, but God used them as his rods to punish his enemies.