Albert Barnes Commentary Zechariah 4:8

"Moreover the word of Jehovah came unto me, saying," — Zechariah 4:8 (ASV)

And the word of the Lord - Keil: “This word of the Lord is not addressed through ‘the interpreting angel,’ but direct from the Lord, and that through the ‘Angel of the Lord’. For though in the first instance the words, the hands of Zerubbabel etc., relate to the building of the material temple and announce its completion through Zerubbabel, yet the inference, and thou shalt know that the Lord of hosts hath sent me unto you, shows that the meaning is not exhausted by it. This indicates that here also this building is mentioned only as a type of the building of the spiritual temple; and the completion of the typical temple is but a pledge of the completion of the true temple. For not through the completion of the material temple, but only through the building of the kingdom of God, foreshadowed by it, can Judah know that the Angel of the Lord was sent to him.”