Adam Clarke on Revelation 22:14

Blessed are they that do his commandments - They are happy who are obedient.

That they may have right to the tree of life - The original is much more expressive, Ἱνα εσται ἡ εξουσια αυτων επι το ξυλον της ζωης· That they may have authority over the tree of life; an authority founded on right, this right founded on obedience to the commandments of God, and that obedience produced by the grace of God working in them. Without grace no obedience; without obedience no authority to the tree of life; without authority no right; without right no enjoyment: God's grace through Christ produces the good, and then rewards it as if all had been our own.