John Gill Commentary Zechariah 2:1

"And I lifted up mine eyes, and saw, and, behold, a man with a measuring line in his hand." — Zechariah 2:1 (ASV)

I lifted up mine eyes again, and looked And saw a third vision; which, as Kimchi owns, refers to the times of the Messiah; though it might be of use to the Jews then present, to encourage them to expect the rebuilding of Jerusalem, in a literal sense.

and behold a man with a measuring line in his hand: by whom is meant, not Nehemiah, nor Zerubbabel; see (Zechariah 4:10) who were concerned in the building of Jerusalem; nor any mere man, nor even a created angel; for, though he may be the same with the other angel, that did not talk with the prophet, (Zechariah 2:3) as Kimchi observes; seeing he seems to be superior to him that did; yet not a ministering spirit, but the Messiah, who in this book is often spoken of as a man; (See Gill on Zechariah 1:8).

And by "the measuring line in his hand" may be meant eternal predestination, the Lamb's book of life, which is in his keeping; and is the measure and rule by which he proceeds in the calling, justification, and glorification of the firstborn, whose names are written in heaven; or the Scriptures of truth, the measure and rule of doctrine, discipline, worship, and conversation; and according to which Christ forms, constitutes, and regulates Gospel churches; see (Ezekiel 40:3) (Revelation 11:1) .