Acts 2:37 → Zechariah 12:10

Zechariah 12:10 names a triad: the LORD pours out "a spirit of grace and prayer" on the house of David, they "look on Me, the One they have pierced," and they mourn for Him. Acts 2 enacts that triad with striking precision on the day of Pentecost. The Spirit is poured out (2:17-18, 33, the Joel-outpouring that 12:10a anticipates); Peter discloses the pierced One — "this Jesus, whom you crucified" (2:23, 36) — to the very inhabitants of Jerusalem; and the hearers, "cut to the heart" (κατενύγησαν, 2:37), cry out in convicted mourning, "Brothers, what shall we do?" This "cut to the heart" is Zechariah's Spirit-wrought lamentation happening in narrative form: the convicting Spirit and the Spirit of grace are the same Spirit, and the looking-upon-the-pierced-one produces exactly the repentant grief Zechariah foretold, which Peter then channels toward the cleansing fountain (Zech 13:1) by summoning them to "repent and be baptized ... for the forgiveness of your sins" (2:38). While Acts 2 cites Joel explicitly, it functions as the first historical installment of Zechariah 12:10's looking-and-mourning — the Pentecostal firstfruits of Israel's eschatological turning to her crucified Messiah. The connection guards the gospel from moralism: the mourning here is not self-generated remorse but a Spirit-given gift of grace that flows from beholding the pierced Savior, and it issues immediately in the joy of forgiveness and the gift of the Spirit. To be cut to the heart over the One we pierced is the doorway to treasuring Him as Lord and Christ.