2 Peter 1:17-18 → Matthew 17:5

This is the rare case of one NT text explicitly recounting an event recorded in an earlier NT text — the warrant for the vault's narrow `NT to NT` category (admitted only for explicit recollection or citation, never synoptic parallels or thematic echoes). Defending the apostolic message against the charge of "cleverly devised myths" (2 Pet 1:16), Peter grounds his eyewitness claim in the Transfiguration: "He received honor and glory from God the Father when the voice came to Him from the Majestic Glory, saying, 'This is My beloved Son, in whom I am well pleased.' And we ourselves heard this voice from heaven when we were with Him on the holy mountain" (2 Pet 1:17-18). The quoted utterance matches Matthew's wording most closely among the Synoptic accounts (Matt 17:5; cf. Mark 9:7; Luke 9:35), itself a fusion of Psalm 2:7 (royal sonship) and Isaiah 42:1 (Servant delight). Whether Peter draws on Matthew's text or on the shared apostolic memory he claims firsthand, the redemptive-historical function is the same: the Transfiguration is presented as the proleptic unveiling of the Son's majesty — the down payment on the Parousia ("the power and coming of our Lord Jesus Christ," 1:16) — which in turn makes "the prophetic word more fully confirmed" (1:19). The voice on the holy mountain stands in the theophany succession of Sinai and Horeb, now climaxing in the Son Himself, until "the day dawns and the morning star rises."