Blessed are those who do His commandments
Those who do is οἱ ποιοῦντες [hoi poiountes] , present tense participle: the ones continually doing. The NU text has blessed are those who wash their robes, which speaks of their sin being cleansed by the blood of Christ (cf. Rev. Rev. 1:5+; Rev. 7:14+).1
Those who are born-again and truly known by the Son are the ones who do the will of the Father:
Not everyone who says to Me, Lord, Lord, shall enter the kingdom of heaven, but he who does the will of My Father in heaven. Many will say to Me in that day, Lord, Lord, have we not prophesied in Your name, cast out demons in Your name, and done many wonders in Your name? And then I will declare to them, I never knew you; depart from Me, you who practice lawlessness! (Mtt. Mat. 7:21-23) [emphasis added]Our blessing does not derive from merely knowing the things of God, but from doing them (John John 13:15 cf. Rev. Rev. 12:17+; Rev. 14:12+). Jesus said that if we love Him, then we will keep His commandments (John John 14:15, John 14:21-23). When we neglect to keep His commandments, we demonstrate our lack of love for Him. Our motivation to keep His commandments is also found in our desire to purify ourselves in preparation for His appearing (1Jn. 1Jn. 3:2-3). The power to keep His commandments is derived from the indwelling Holy Spirit (1Jn. 1Jn. 3:24). If we call him Lord, but do not keep His commandments, we are schizophrenic. How can He be Lord when we will not obey Him (Luke Luke 6:46)? Worse than that, we are found to be liars concerning our relationship with Him:
Now by this we know that we know Him, if we keep His commandments. He who says, I know Him, and does not keep His commandments, is a liar, and the truth is not in him. (1Jn. 1Jn. 2:3-4)
Therefore lay aside all filthiness and overflow of wickedness, and receive with meekness the implanted word, which is able to save your souls. But be doers of the word, and not hearers only, deceiving yourselves. For if anyone is a hearer of the word and not a doer, he is like a man observing his natural face in a mirror; for he observes himself, goes away, and immediately forgets what kind of man he was. (Jas. Jas. 1:21-24)This is one of seven blessings given within the book of Revelation. See commentary on Revelation 1:3.
that they may have the right to the tree of life
They may have the right to the tree of life is ἔσται ἡ ἐξουσία αὐτῶν ἐπὶ [estai hē exousia autōn epi] : it will be the authority of them over the tree of life. The right to the tree of life is universal to all believers. No mention is made of two categories of the redeemed in eternity: those who require access to the tree and those who do not. Neither is there mention of some who eat the fruit and others who only use the leaves. See commentary on Revelation 22:2.
may enter through the gates into the city.
Those who are born-again are the overcomers. Through the power of the Holy Spirit they will also be those who do the commands of the Lord. They are among the redeemed who are written in the Book of Life and therefore avoid the second death which is being cast into the Lake of Fire (Rev. Rev. 21:15+). They have full access to the New Jerusalem whose gates are never closed (Rev. Rev. 21:24-26+). All the redeemed have access through the gates. Access through the gates is equivalent with rights to the tree of life because the tree is within the city. To access the tree, one must first go through the gates. See commentary on Revelation 21:24.
1 The [TR] reading appears to be a scribal emendation, for elsewhere the author uses the expression τηρεῖν τὰς ἐντολάς [tērein tas entolas] (Rev. Rev. 12:17+; Rev. 14:12+).Bruce M. Metzger, A Textual Commentary on the Greek New Testament (Stuttgart, Germany: Deutsche Bibelgesellschaft, 1994), Rev. 22:14.