Seven instances as follows (NWT/BSB):
(Genesis 2:9) Thus Jehovah God made to grow out of the ground every tree pleasing to look at and good for food and also the tree of life in the middle of the garden and the tree of the knowledge of good and bad.
(Genesis 3:22-24) Jehovah God then said: “Here the man has become like one of us in knowing good and bad. Now in order that he may not put his hand out and take fruit also from the tree of life and eat and live to forever,—” 23 With that Jehovah God expelled him from the garden of Eden to cultivate the ground from which he had been taken. 24 So he drove the man out, and he posted at the east of the garden of Eden the cherubs and the flaming blade of a sword that was turning continuously to guard the way to the tree of life.
(Revelation 2:7) He who has an ear, let him hear what the Spirit says to the churches: To the one who overcomes, I will grant the right to eat from the tree of life, in the Paradise of God.’ (which is in the paradise of God – NWT)
(Revelation 22:1, 2) Then the angel showed me a river of the water of life, as clear as crystal, flowing from the throne of God and of the Lamb 2 down the middle of the main street of the city. On either side of the river stood a tree of life, bearing twelve kinds of fruit and yielding a fresh crop for each month. And the leaves of the tree [of life] are for the healing of the nations.
(Revelation 22:14) Blessed are those who wash their robes, so that they have the right to the tree of life and may enter the city by its gates.
In 22:2 we have a conundrum. The first instance of this tree has no definite article, but both the second instance, and the case in v14 do. Strictly speaking BSB is correct in translating it as 1. a tree of life 2. the tree of life and 3. the tree of life, if my understanding of the finer points of Greek grammar is correct (doubtful!). The problem appears to be one of logic (although bear in mind that Revelation is written in signs so nothing really has to be constrained by physicality). How can the tree of life be on both banks, either side, of the river (with definite article)? By translating ‘a tree of life’ BSB gives the impression that there are two trees of life, one on each bank, but then by reverting to the singular later in the verse leaves the reader slightly confused. NIV translates v2 as ‘on each side of the river stood the tree of life’, but then how can one tree be on both banks of any river? NWT chickens out and mistranslates it in the plural, ‘trees of life’. At least in the reference edition a footnote explained this, but such helpful tools have long since been removed from newer editions. It seems to me that the tree of life that was in Eden, was removed at some unspecified time prior to the flood, taken away from the earthly realm and placed in New Jerusalem. It then returns to earth when John sees New Jerusalem descending from heaven (21:2). It is the very same tree that has been taken away from the earth, both for safe-keeping and to prevent humankind from eating of its life-giving fruit. I prefer the NIV translation – the tree of life on each side of the river. It is enigmatic, it inspires curiosity, we ask the obvious question and then we delve, ponder and wonder. It is what Jehovah wants us to do! Yet we are not required to be dogmatic about things that perhaps we will only discover in the fullness of time. It strikes me that in v1, John was shown ‘a river of life’. Are there many of such rivers? Is it one river that has several tributaries? That is unlikely as it flows from a single point, the throne. Does it fan out like a delta? Could it be that this tree is a collective tree, with several instances of it, cloned if you like, that sprout wherever required? Maybe in Eden, with only one man and one woman, one instance of the tree was sufficient, whereas in New Jerusalem with it large size and innumerable great crowd, many instances, all genetically identical, can be provided wherever they are needed. The possibilities are endless!
Why are there seven mentions of this tree? The number seven has great significance in scripture. Here is a comment from Insight:
Seven. Seven is used frequently in the Scriptures to signify completeness. At times it has reference to bringing a work toward completion. Or it can refer to the complete cycle of things as established or allowed by God. By completing his work toward the earth in six creative days and resting on the seventh day, Jehovah set the pattern for the whole Sabbath arrangement, from the seven-day week to the Jubilee year that followed the seven-times-seven–year cycle. (it-2 p. 512 Number, Numeral)
This article mentions various other sevens: the seven-day duration of certain festivals, the seven congregations of Revelation, the seven heads of the wild beast, marching around Jericho for seven days, Naaman bathing seven times, and many more. So what is the answer to our question? It is hard to say, really, but it seems significant. If the tree represents the entirety of God’s grace toward mankind, the complete set of provisions required to live according to God’s purpose, then naming it seven times might be appropriate.
What is the purpose of the tree of life? Initially it was in the middle of the garden of Eden, alongside the tree of knowledge. Was it one of the trees that were good for food? Possibly, although NWT adds ‘also’ as if possibly not (Gen 2:9). However, at Genesis 2:17 it is worth noting that it was only the tree of knowledge that was prohibited as food. So had Adam and his wife been eating its fruitage up until the fateful moment that she succumbed to the serpentine lie? Subsequently, Jehovah felt that the tree of life had to be secured and access prevented that they may not eat and live to time indefinite (3:22). So having expelled the ungrateful couple from the garden, he placed a flaming sword to deny unauthorised admittance (3:24). The tree then exits the Bible account reappearing only in the grand finale of Revelation.
In chapter 21 John sees New Jerusalem descending to earth. God then dwells with mankind and removes death, mourning and pain to prove that the former things really have passed away. This is a new beginning. We are then given a view inside the walls. The first notable feature is that there is no temple in this city, unlike the original. The throne of God and of the Lamb is there (yes, they come to earth to be with us – heaven is here in His presence), flowing from which is a river of life in proximity to the tree of life. It yields twelve crops of fruit and its leaves are for the curing of the nations. Why has it returned? The answer is found in 22:14
‘Blessed are those who wash their robes, so that they may have the right to the tree of life and may enter the city by its gates’ (BSB).
But who? Initially this is a great crowd that survives the great tribulation; they are before God’s throne wearing white robes that have been washed in the blood of the Lamb (7:14). Are these mentioned in 22:14 the same group as the chapter seven group, or others? As the separating of the sheep and goats apparently takes place during the millennium, it could be a further group of ovine people who during that time, free of all Satanic influence, also wash their robes by exercising faith in the Lamb, and who have their faith tested during the siege of the camp of the saints and are then granted the right, the authority, to enter New Jerusalem and eat of the tree of life. This right to the tree is an important benefit, worth highlighting. God is faithful, that is, he absolutely guarantees that what he purposes will come to pass. He sent his son to earth because of his love for mankind that they might gain the everlasting life that Adam wasted (Jo 3:16). Jesus arrived, willingly endured humiliation and death, that through his blood all those exercising faith, repenting of their sins and being reborn through water and spirit, would have the right to live forever as children of God. Everyone who engages in this process, and is thus adopted, has the legal right to eat of the tree of life, in New Jerusalem, and live forever, right here, on earth, in the presence of God and of the Lamb. What an utterly amazing prospect!
In between these two groups of three is the mention of this tree of life at Revelation 2:7. This is part of the letter from Jesus to the congregation in Ephesus. They had been doing well, but their first love had cooled and been abandoned. They needed to ‘repent and perform the deeds you did at first’ (2:5). ‘To the one who overcomes, I will grant the right to eat from the tree of life in the Paradise of God’ (2:7). The tree of life represents eternal life and divine blessing. John’s vision is the revealing of how what was lost through sin will be fully restored in the Paradise of God. The term ‘paradise’ describes a place of perfect peace and communion with God. It appears just four times in the Bible (Ca 4:13, Lu 23:43, 2 Co 12:4, Rev 2:7). Solomon uses it illustratively; Jesus promised the criminal life in paradise; Paul was somehow caught away to paradise; and Jesus assures the Ephesians that the tree of life is still in paradise. In order to eat of its fruit they too must enter paradise. Not only are they allowed in, but they have the right to enter and eat. Who else is in this paradise, later called New Jerusalem? Well, both God and the Lamb. Just as Jehovah lived and walked in the garden with Adam, spoke with him, worked alongside him, provided him with a wife from his own flesh, so too those who overcome, who endure as Jesus endured (Heb 12:2) and whose love remains ardent will have the right to eat of the tree of life, right here on earth, in the presence of Jehovah and Jesus.
A further comment on New Jerusalem. Firstly it is new. It is not the old one here in the Middle East somehow renovated and refurbished. It is entirely new, untainted by all the things that have gone before. Yes, Jerusalem was the scene of Jehovah’s glorious presence on the rare occasions that his people devoted themselves to pure worship. But mostly its history is one of rebellion, state of siege, bloodshed and appalling slaughter. This New Jerusalem is a shiny new one, brand new, entirely unsullied by the past.
When it arrives, its direction is downward. Heaven extends itself down to and touches earth. Just as every perfect present comes down from the Father (Jas 1:17), New Jerusalem is his ultimate gift. When Jesus prayed ‘let your kingdom come’ he meant just this. God’s heavenly kingdom would come down to earth so that his will would be accomplished here. Redemption therefore culminates, not in our escape to the clouds, but in God relocating to earth and establishing his dwelling and presence here among us, on a new earth – perhaps actually new, perhaps refurbished and restored, who knows? New Jerusalem as described does not initially fill the whole earth, but an area of around 2m square miles (about the size of Europe excluding the former Soviet parts). This creates a secure space of holiness, whilst those outside, those still learning, refusing to learn, or being given a second chance, are prevented from disturbing the peace. Ultimately, after the millennium and the destruction of Satan and death itself, it will expand to fill the entire earth.
Lexical notes on the Greek word ouranos, heaven
Strong 3772
Origin – perhaps from an obsolete oro, to rise up through the idea of elevation.
1. the sky
2. by extension, heaven (as the abode of God)
3. by implication, happiness, power, eternity
4. specially, the gospel (Christianity)
Thayer
1. the vaulted expanse of the sky with all the things visible in it;
a. generally: as opposed to the earth
b. the aerial heavens (region of clouds, tempest, thunder and lightning);
c. the sidereal or starry heavens;
2. the region above the sidereal heavens, the seat of an order of things eternal and consummately perfect, where God dwells and other heavenly beings;