Rashi on Psalms
You rebuked nations [This alludes to Amalek, described in Num. 24:20 as] “Amalek is the first of the nations.”
Radak on Psalms
Thou hast rebuked the nations (גוִֹיִם גערת): – (The expression for) rebuke when used without the preposition beth has the meaning of destruction, as: "Rebuke the wild beast of the reed" (Ps. 68:31); and as, "Behold, I will rebuke the seed for your sake" (Mal. 2:3); and so Thou hast rebuked (the) nations here.