A.T. Robertson Commentary Revelation 11:1

"And there was given me a reed like unto a rod: and one said, Rise, and measure the temple of God, and the altar, and them that worship therein." — Revelation 11:1 (ASV)

A reed (καλαμος). Old word for a growing reed (Matthew 11:7) which grew in immense brakes in the Jordan valley, a writer's reed (3 John 1:7), a measuring-rod (here, 21:15f.; Ezekiel 40:3–6; Ezekiel 42:16–19).

Like a rod (ομοιος ραβδω). See 2:27; Mr 6:8 for ραβδος.

And one said (λεγων). "Saying" (present active masculine participle of λεγω) is all that the Greek has. The participle implies εδωκεν (he gave), not εδοθη, a harsh construction seen in Ge 22:20; 38:24, etc.

Rise and measure (εγειρε κα μετρησον). Present active imperative of εγειρω (intransitive, exclamatory use as in Mr 2:11) and first aorist active imperative of μετρεω. In Eze 42:2ff. the prophet measures the temple and that passage is probably in mind here. But modern scholars do not know how to interpret this interlude (11:1-13) before the seventh trumpet (11:15). Some (Wellhausen) take it to be a scrap from the Zealot party before the destruction of Jerusalem, which event Christ also foretold (Matthew 24:2; Luke 21:6) and which was also attributed to Stephen (Acts 6:14). Charles denies any possible literal interpretation and takes the language in a wholly eschatological sense. There are three points in the interlude, however understood: the chastisement of Jerusalem or Israel (verses 1,2), the mission of the two witnesses (3-12), the rescue of the remnant (13). There is a heavenly sanctuary (7:15; 11:19; 14:15, etc.), but here ναος is on earth and yet not the actual temple in Jerusalem (unless so interpreted). Perhaps here it is the spiritual (3:12; 2 Thessalonians 2:4; 1 Corinthians 3:16f.; 2 Corinthians 6:16; Ephesians 2:19ff.). For altar (θυσιαστηριον) see 8:3. Perhaps measuring as applied to "them that worship therein" (τους προσκυνουντας εν αυτω) implies a word like numbering, with an allusion to the 144,000 in chapter 7 (a zeugma).