Jamieson, Fausset and Brown on John 17:4-5

4-5. I have glorified thee on the earth--rather, "I glorified" (for the thing is conceived as now past).

I have finished--I finished.

the work which thou gavest me to do--It is very important to preserve in the translation the past tense, used in the original, otherwise it might be thought that the work already "finished" was only what He had done before uttering that prayer; whereas it will be observed that our Lord speaks throughout as already beyond this present scene (Joh 17:12, &c.), and so must be supposed to include in His "finished work" the "decease which He was to accomplish at Jerusalem."