The washing of robes as mentioned in Revelation 22:14 is a metaphor for purification from uncleanliness, meaning sin. This verse pronounces a blessing on those who are cleansed from their sin through the process of sanctification. This is the work of God through His Holy Spirit.
Or do you not know that the unrighteous will not inherit the kingdom of God? Do not be deceived: neither the sexually immoral, nor idolaters, nor adulterers, nor men who practice homosexuality, nor thieves, nor the greedy, nor drunkards, nor revilers, nor swindlers will inherit the kingdom of God. And such were some of you. But you were washed, you were sanctified, you were justified in the name of the Lord Jesus Christ and by the Spirit of our God. (1 Corinthians 6:9-11 ESV)
