Revelation 5:10 → Exodus 19:6

At Sinai, before the Decalogue, Yahweh defines Israel's vocation in words: "you shall be a kingdom of priests and a holy nation" (mamleket kōhănîm, LXX βασίλειον ἱεράτευμα) — a corporate royal-priesthood drawn "out of all the nations" (Exod 19:5-6), conferred as identity yet held under the condition "if you will indeed obey My voice." In the heavenly throne-room the redeemed sing a new song to the slain Lamb, and John reworks that very Sinai formula into the doxological ἐποίησας... βασιλείαν καὶ ἱερεῖς — "You have made them to be a kingdom and priests to serve our God, and they will reign upon the earth" (Rev 5:10). Because John recasts the Sinai phrase — following the Hebrew mamleket kōhănîm ("kingdom … priests") rather than the LXX's βασίλειον ἱεράτευμα, with which it shares no Greek vocabulary — into his own apocalyptic idiom (fused here with the reigning-saints motif of Daniel 7:22, 27) rather than citing it verbatim with a formula, this is an Allusion, not a Direct Quotation. The connecting method is Promise-Fulfillment carried on a canon-wide Longitudinal Theme (Kingdom / Holiness): the spoken Sinai vocation is what the Lamb's purchasing blood (5:9) realizes for a people "from every tribe and tongue and people and nation" — and so this is Promise-Fulfillment, not typology, for what travels is a verbal calling brought to its eschatological accomplishment, with only a secondary Contrast (Israel's conditional, unattained office versus the Lamb's accomplished reign). What Sinai could only describe and demand, the Lamb has made (ἐποίησας, accomplished fact) — and the deletion-test lands not in a foreshadow but in the song itself: the redeemed do not merely possess a priestly office, they delight to "serve our God" and reign with Him, so that the glory of the One who was slain and bought them becomes the very content of their unending worship — the kingdom-of-priests vocation consummated as joy in the Lamb.