A.T. Robertson Commentary Revelation 3:10

"Because thou didst keep the word of my patience, I also will keep thee from the hour of trial, that [hour] which is to come upon the whole world, to try them that dwell upon the earth." — Revelation 3:10 (ASV)

Patience (υπομενης). "Endurance" as in 13:10; 14:12 as also in 2 Thessalonians 3:5.

Thou didst keep (ετηρησας)

--I also will keep (καγω τηρησω). Aorist active indicative and future active corresponding to each other. For a like play on the tenses of this verb by Christ see Joh 17:6 (τετηρηκαν), John 17:11 (τηρησον), John 17:12 (ετηρουν).

From the hour of trial (εκ της ωρας του πειρασμου). This use of εκ after τηρεω in Joh 17:15, απο in Jas 1:27. Trial brings temptation often (James 1:2,13). Jesus endured (Hebrews 12:1f.) and he will help them. There is still a church in Philadelphia in spite of the Turks.

Which is to come (της μελλουσης ερχεσθα). Agreeing with ωρας (feminine), not with πειρασμου (masculine).

Upon the whole world (επ της εποικουμενης ολης). The inhabited earth (γης) as in Re 12:19; Luke 2:1; Acts 16:6, etc.), not the physical earth, but the world of men as explained by the next clause.

To try (πειρασα). First aorist active infinitive of purpose from πειραζω, probably to tempt (cf. the demons in 9:1-21), not merely to afflict (2:10).

That dwell upon the earth (τους κατοικουντας επ της γης). Present active articular participle of κατοικεω, explaining "the whole world" just before.