Revelation 22:2-3:
In the midst of the street of it, and on either side of the river, was there the tree of life, which bare twelve manner of fruits, and yielded her fruit every month: and the leaves of the tree were for the healing of the nations.
And there shall be no more curse: but the throne of God and of the Lamb shall be in it; and his servants shall serve him.
Notes on Revelation 22:2-3:
There will be no more curse on the new earth. There will be no more sickness, which is explicitly part of the curse for breaking the Law. Because Satan (the author of sickness) and sin (without which there is no sickness) will not be on the new earth, sickness will not be around for you to catch.
I don’t claim to have a definitive explanation for the leaves on the tree being for the healing of the nations. Some things are not explained in detail in Scripture. At least I can say that anything that is from God produces healing, not sickness. (The question of why healing leaves are in a place where there is no sickness is handled in the answer to the question below.)
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