In this verse the psalmist prays that Yahweh punish (Remember … against) the Edomites for the help they gave to the Babylonians in the capture and destruction of Jerusalem in 587 B.C. (see Obadiah 10-14; Ezek 25.12-14; 35.5-9). The Edomites, who lived to the south of Judah (in Edom), were descendants of Esau and thus were related to the Israelites. The day of Jerusalem has been rendered clearly by Good News Translation‘s “the day Jerusalem was captured.” In languages which will not use the passive here, it may be necessary to say “Remember what the people of Edom did the day the Babylonians captured Jerusalem.” The Hebrew word translated raze means “to lay bare, uncover.” It is quite possible that there is a play on words here and, as Dahood suggests, Jerusalem is compared to a woman; the command reads “strip her to her buttocks” (see New Jerusalem Bible “Strip her, strip her, to her very foundations!”). In any case, the capture and destruction of Jerusalem by the Babylonians in 587 B.C. is meant.

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 .