Read Ezekiel 47-48 at Bible Gateway.
Then he brought me back to the door of the temple; and there was water, flowing from under the threshold of the temple toward the east, for the front of the temple faced east; the water was flowing from under the right side of the temple, south of the altar. Eze 47:1
Then he said to me: “This water flows toward the eastern region, goes down into the valley, and enters the sea. When it reaches the sea, its waters are healed. And it shall be that every living thing that moves, wherever the rivers go, will live.” Eze 47:8-9
“Along the bank of the river, on this side and that, will grow all kinds of trees used for food; their leaves will not wither, and their fruit will not fail. They will bear fruit every month, because their water flows from the sanctuary. Their fruit will be for food, and their leaves for medicine.” Eze 47:12
This living river appears more than once in Scripture:
And he showed me a pure river of water of life, clear as crystal, proceeding from the throne of God and of the Lamb. In the middle of its street, and on either side of the river, was the tree of life, which bore twelve fruits, each tree yielding its fruit every month. The leaves of the tree were for the healing of the nations. Rev 22:1-2
By thematic connection, one of the teaching tools of Scripture, we understand that John is seeing the same river that Ezekiel saw, when he sees the vision of the New Jerusalem, of which he says:
But I saw no temple in it, for the Lord God Almighty and the Lamb are its temple. Rev 21:22
(This same river of life and tree of life are also in Eden, Gen 2:10.) If Ezekiel and John are seeing the same thing, then the temple that Ezekiel is seeing, reveals and describes the Lord God Almighty and the Lamb. John does not see a physical building, because the Lamb who was slain had come, and John saw the Lamb. The Lamb is the temple. Ezekiel saw the Lamb in the form of a physical building, because He had not yet come, and the Lamb is revealed covertly, not overtly, before His coming. For if the rulers of the age had known what they were doing, they would not have crucified the Lord of glory (1 Cor 2:7-8).
I do not believe, unlike many who teach on the end times, that Ezekiel’s temple is a third or even a fourth temple, a physical building, that will be built. The temple that Ezekiel is seeing, is the Lamb who was slain from the foundation of the world. The river of life may be an actual river in the New Jerusalem, but it is also the living water, the Holy Spirit, who proceeds from the Father and the Son, proceeding from the throne of God and of the Lamb. For every living thing that moves, wherever the river of the Holy Spirit goes, will live. He is the One who causes the flesh and breath of life to come upon the dry bones, so that they live!
Hallelujah! Thank You God!