In the eighth month - o. The date joins on Zechariah’s prophecy to those of Haggai. Two months before, “in the sixth month” Haggai 1:1, had Haggai, conjointly with Zechariah Ezra 5:1-2, exhorted Zerubbabel and the people to resume the intermitted building of the temple. These had used such diligence, notwithstanding the partial discouragement of the Persian Government, that God gave them “in the seventh month” Ezra 5:3-5, the magnificent promise of the later glory of the temple through the coming of Christ Haggai 2:1-9. Still, as Haggai too warned them, the conversion was not complete. So Zechariah in the eighth, as Haggai in the ninth Haggai 2:10-14 month, urges upon them the necessity of thorough and inward repentance, as the condition of partaking of those promises.
Osorius: “Thrice in the course of one saying, he mentions the most holy name of God; partly to instruct in the knowledge of Three Persons in one Nature, partly to confirm their minds more strongly in the hope of the salvation to come.”