Acts 2 foregrounds intelligible multilingual hearing; it should not be reduced to a private ecstatic prayer language. Babel reversal is a strong canonical mirror, not an explicit quotation. The feast itself is Jewish Shavuot/Pentecost, placing the Spirit’s outpouring inside Israel’s sacred calendar rather than outside it.

Test the tradition: The tongues in Acts 2 are merely a private ecstatic prayer language unintelligible to human hearers. For Acts 2, emphasize intelligible multilingual hearing; do not use this one scene to erase other NT phenomena.

Feast fulfillment calibration: Pentecost is both a real Jewish feast day and the day Acts narrates the Spirit’s dramatic outpouring. Peter’s explicit fulfillment text is Joel, not Leviticus 23. Sinai and Babel echoes deepen the scene, but they should not be upgraded into quotation or exact one-to-one ritual fulfillment where Luke does not say so.