A.T. Robertson Commentary Revelation 22:3

"And there shall be no curse any more: and the throne of God and of the Lamb shall be therein: and his servants shall serve him;" — Revelation 22:3 (ASV)

There shall be no curse any more (παν καταθεμα ουκ εστα ετ). No other example of καταθεμα has been found outside of the Didache XVI. 5, though the verb καταθεματιζω occurs in Mt 26:74, meaning to curse, while we have αναθεματιζω in Mr 14:71 in the same sense. It may be a syncopated form of καταναθεμα. The usual αναθεμα (curse) occurs in 1 Corinthians 16:22; Galatians 1:8; Romans 9:3. For παν with ουκ=ουδεν see 21:27.

Shall do him service (λατρευσουσιν αυτω). Future active of λατρευω, linear idea, "shall keep on serving." See 7:15 for present active indicative of this same verb with the dative αυτω as here, picturing the worship of God in heaven. See 27:1 for "the throne of God and of the Lamb."