In these verses the psalmist wishes a curse on Babylon, called here either “Daughter Babylon” (Dahood) or daughter of Babylon (Revised Standard Version); New Jerusalem Bible has “Fair Babylon” (see the same idiom discussed in 9.14; 45.12). Daughter of Babylon can refer to the people of Babylon, and in many languages it will have to be translated in that manner. On the basis of a possible allusion of the rock to Petra, the capital of Edom, some take daughter of Babylon to refer to Edom (see footnote “g” to verse 9 in Traduction œcuménique de la Bible). This does not seem very likely.
After Babylon the Hebrew has the passive form of the verb “to destroy”; so Good News Translation “you will be destroyed” (also Biblia Dios Habla Hoy, Bible en français courant, Bible de Jérusalem; similarly Traduction œcuménique de la Bible “destined to destruction”; and New Jerusalem Bible “doomed to destruction”). Some of the ancient versions read the active form “destroyer” (so Revised Standard Version, New Jerusalem Bible, New English Bible, New American Bible, Dahood, Weiser). Either sense is appropriate; as Anderson says, however, the active form seems more appropriate. Hebrew Old Testament Text Project prefers the passive form of the Hebrew text: “you who are to be devastated.”
Line b is an example of the law that required that the punishment fit the crime, the lex talionis, a “tit for tat” (see Lev 24.19-20). Good News Translation would have done better by translating “Happy is the one who does to you what you did to us.” For Happy see the comments on “Blessed” in 1.1. A possible translation here is “He will do well who….”
The gruesome “blessing” (curse) pronounced in verse 9 is to be understood in its context; it was not uncommon for victorious armies to kill the children–especially the male children–of their conquered enemies (see 2 Kgs 8.12; Isa 13.16; Hos 13.16; Nah 3.10). Good News Translation has connected verse 9 with verse 8, to form one sentence; it is better to make verse 9 a complete and separate sentence, another “blessing.” Verse 9 contains two wishes for vengeance. These are the same as curses, but their result is intended to bring happiness to the avenger. In some languages it will be necessary to appeal to God as the one who will provide the reward of happiness; for example, “Let God make the person happy who does to you the bad things you did to us. Let God make the person happy who takes your babies and smashes them against a rock.”
Quoted with permission from Bratcher, Robert G. and Reyburn, William D. A Handbook on the Book of Psalms. (UBS Helps for Translators). New York: UBS, 1991. For this and other handbooks for translators see here .