'Tree of Life' in the Bible

He that hath an ear, let him hear what the Spirit saith to the churches; To him that overcometh will I give to eat of the tree of life, which is in the midst of the paradise of God.

In the midst of the street of it, and on each side of the river, was there the tree of life, which bore twelve kinds of fruits, and yielded her fruit every month: and the leaves of the tree were for the healing of the nations.

Blessed are they that do his commandments, that they may have right to the tree of life, and may enter in through the gates into the city.