The first section of Zechariah 12 (verses 2-8) promises Israel a new Exodus as the Angel of Yahweh will lead them into the safety of their land free from the oppression of the nations. This is the eschatological hope of Israel.
Zechariah 12:9 functions as a segway between this hopeful proclamation and the spiritual renewal of Israel. “On the day” that God purposes to destroy the nations hostile to Jerusalem, God will also rejuvenate Israel’s spiritual life through lamentation.
God will “pour out…a S(s)pirit of grace and supplication” upon the royal house of David and upon Jerusalem. This promise resonates with Joel (2:28-30) and Ezekiel (39:29) who also envisioned a time when God will pour out a gracious Spirit upon Israel. This is the renewal of Israel as they experience God’s grace and turn to God in supplication. The grace of God will turn the dynastic house of David and Jerusalem to Yahweh. God’s redemption will turn the hearts of Israel to their God.
Israel will respond to this gracious outpouring. They will mourn the one whom they pierced. The phrase containing the “pierced one” is notoriously difficult. Historically a Messianic text in both Jewish and Christian interpretation, the exact translation and its resultant meaning is problematic.
The text may read either that they will look “to” (ASV) or “on” (NIV) either “me” (NIV) or “him” (RSV; JB). The relative clause “whom they have pierced” may either refer to the one “upon” or the one “to” whom they look (NASB) or to another whom they lament as they look to “me” (JPS). The difficulties are too complex to explain for the purposes of this post, but it is important to say something for the sake of understanding.
Yahweh is the speaker, and the traditional text reads that they (the house of David and Jerusalem) will look to or upon Yahweh (“me”). If this is the correct reading, Israel—by the grace of God—has been reoriented toward Yahweh as they look to their God for redemption. It is possible, however, that “me” should read “him” (as some Hebrew MSS do). Either way, the pierced one is either Yahweh or Yahweh’s servant (martyr).
The occasion for this reorientation is lament. Israel laments the pierced one. Is the “pierced one” Yahweh? If so, it is a metaphorical expression in Zechariah for the pain which Israel caused Yahweh. But the Hebrew may mean that Israel looks to Yahweh concerning the “pierced one,” that is, they mourn the pierced one whom Yahweh sent. Again, either way, the “pierced one” is the object of mourning.
Early Christians, as in John 19:37 and Revelation 1:7, identified the “pierced one” as Jesus. The Gospel of John associates this piercing with the thrust of the spear into the side of Jesus as the nations (Roman soldiers) and Jewish leaders (chief priests and rulers) watched. Revelation 1:7 applies this text—in combination with Daniel 7:13—in an eschatological context. When Jesus returns—when every eye will see him—“those who pierced him” will also see him and “all the peoples of the earth will mourn because of him.”
The New Testament, then, applies Zechariah 12:10 in two contexts: (1) the crucifixion of Jesus itself and (2) the eschatological return of Jesus. Everyone, not just Israel, will see the pierced one, and everyone, not just Israel, will mourn. In both cases Jesus is the “pierced” servant of Yahweh. Though the nations and Israel—everyone–looked upon his death with satisfaction, in the eschatological day of which Zechariah and Revelation speak they will mourn that same piercing. All the earth will recognize Jesus as the servant of Yahweh.
In the light of this piercing, Israel, according to Zechariah, will mourn. It will be a boundless mourning like morning for your “firstborn,” but even more like mourning for your only child. The language of “firstborn” echoes the Exodus narrative (and also anticipates Jesus as Yahweh’s firstborn), but also reminds us that Israel is Yahweh’s firstborn. But more pointedly, to mourn one’s only child is to mourn the loss of one’s family lineage. It is to mourn the loss of the family’s future.
That mourning is described as similar to the practice of a pagan lamentation well-known to Israel. Hadad is the Aramaic version of the storm God, Baal. Syria’s (Aram) rulers were often named after this God who first appears in the Gilgamesh Epic. Apparently, there was a well-known lamentation ritual practiced at Megiddo which would parallel the kind of mourning Israel would experience in the light of the pierced one. (Some think this lamentation actually refers back to the death of Josiah at Megiddo which ended the hopes that Israel might yet avoid exile, and his death was still lamented in the postexilic period; cf. 2 Chronicles 35:25.)
The whole of Israel—the whole land, including wives—will mourn. More specifically, the houses of David (royal dynasty), Nathan (prophets), Levi (priests) and Shimei will mourn. Why are these mentioned? These are the houses associated with the coronation of Solomon (cf. Dean R. Ulrich, WTJ 72  251-265). The house of David had not faired well since the accession of Solomon. The royal house of David, and consequently involving the temple and Jerusalem, became a covenant-breaker; it degenerated into faithlessness. But now those institutions, on the day God pours out redemption upon Israel, will mourn the one they pierced and turn again to Yahweh in faith and covenant loyalty.
“On that day” (13:1), the day of repentance and mourning, a cleansing fountain will flow over the house of David and Jerusalem for the forgiveness of their sins. God will forgive and cleanse Israel from sin.
The promised renewal in Zechariah 12:2-8 will usher in a time of general repentance, cleansing and forgiveness. It is the reconciliation of Israel with their God. Israel will, on that day, mourn the piercing of Yahweh’s servant. Their lament will also signify their redemption. God will remember the promise to Israel.