Rashi on Psalms
The Lord is King forever and ever after the nations perish from His land.
Radak on Psalms
The Lord is King for ever and ever: – When Thou shalt execute judgment upon the wicked who oppress Israel in exile, then Thou shalt be King for ever and ever and none shall rebel against Thy word, as it says (Zech. 14:9), "And the Lord shall be King over all the earth "; and then
Radak on Psalms
The heathen are perished out of his land: – and the kingdom shall return to Israel.