I will rescue my people from the land of the rising sun and bring them back to dwell in Jerusalem. They shall be my people and I will be their God. Prophet Zechariah after whom the Book of Zechariah is named was among the post-exilic prophets who plied their trade soon after the community’s return from exile. Together with his contemporaries, he was instrumental in the rebuilding of the Temple. As a prophet, his primary responsibility was seeing to it that the post-exilic community was also “rebuilt.” The prophets achieved this by continuing to relay to the people oracles from God. The oracles contained messages of comfort and encouragement. In the passage we have read today, in addition to the many wonderful images that the oracle from the Lord painted, we encounter one of the iconic phrases (statements) that summed up the relationship that existed between Israel and God. The phrase, “ They shall be my people and I will be their God” was no ordinary statement. It was a set of words that described the covenantal relationship that bound Israel to her God (cf. Deuteronomy 26:16-19. The phrase is a set of words which cannot be taken back once they have been uttered. Although they are words that demanded action (responsibility) from the hearer, they were nonetheless being repeatedly uttered by the Lord as words of assurance, comfort and encouragement. 
The “rebuilding” and reconstitution of the post-exilic community was going to be a process. There were many questions that still needed to be answered (why were they carted off into exile; why did the Lord allow his holy dwelling place to be desecrated by pagans; was God still with this community, etc.). The words of assurances by the Lord were thus meant to be part of this “rebuilding” process. By uttering the very words that had been uttered in the ratification of the covenant (cf. Genesis 17:7; Exodus 6:7), the Lord was telling the post-exilic community that he was establishing with them a “new” covenant just as he had done with their ancestors. They were going to be a special people to him just as their ancestors had been.