Revelation 21:3
And I heard a great voice out of heaven saying, Behold, the tabernacle of God is with men, and he will dwell with them, and they shall be his people, and God himself shall be with them, and be their God. (Revelation 21:3)
Dwell.
 Gr. skēnoō (see above on “tabernacle”). With this verse compare Eze. 37:27. Ezekiel describes conditions as they might have been; John, conditions as they will be fulfilled.
With men.
Later in the verse the phrase “with them” appears twice. Three times in this verse the apostle uses the preposition “with,” thereby stressing the amazing fact of God keeping company with men throughout eternity, making His home with them.
Tabernacle.
 Gr. skēnē, “tent,” “booth,” “tabernacle.” The verb skēnoō, “to tent,” “to dwell,” appears in John 1:14: “The Word was made flesh, and dwelt among us” (see comment there). This visible presence of God was made plain by the Shekinah in the days of the theocracy, and later by the personal appearance of Jesus Christ as a member of the human family, dwelling among men. The great voice from heaven now stresses the wonderful fact of a new creation and of God dwelling personally with His people.
Great voice.
The speaker is not identified. It is presumably not God, for He is spoken of in the third person.