John the Apostle
Revelation 11:1BSB·traditional attribution

Then I was given a measuring rod like a staff and was told, “Go and measure the temple of God and the altar, and count the number of worshipers there.

Matthew Henry Presbyterian @wholebiblehenry

This prophetical passage about measuring the temple is a plain reference to what we find in Ezekiel's vision, Eze 40:3, etc. But how to understand either the one or the other is not so easy. It should seem the design of measuring the temple in the former case was in order to the rebuilding of it, and that with advantage; the design of this measurement seems to be either, 1.

Commenting on Revelation 11:1-2

John Gill Reformed Baptist @doctorgill

And there was given me a reed like unto a rod,.... A measuring reed, which with the Jews was six cubits long, Eze 40:5; with the Greeks and Romans, ten feet long; the Ethiopic version here calls it a "golden reed", as in Rev 21:15.

Albert Barnes Presbyterian @notesbybarnes

CHAPTER XI ANALYSIS OF THE CHAPTER THIS chapter, which is very improperly separated from the preceding, and improperly ended--for it should have been closed at ver. 18-- consists (excluding the last verse, which properly belongs to the succeeding chapter) essentially of three parts:-- I. The measuring of the temple, . A reed, or measuring- stick, is given to John, and he is directed to arise and measure the temple.