We are up to the final attribute. V’Nakeh which means that He cleanses. Nikayon means to clean. Rashi says that it means He cleanses those that sin from their punishment and from the sin,
Rabbenu Bachye adds that it means that even if a person goes back to sin after teshuva and God had forgiven him, and he repeated this sin, God doesn't go back to the sin. Those sins have been forgiven and we start a clean slate.
That's important, because although we don't plan on sinning again after Yom Kippur, and we really are serious about our teshuva, and we really regret, and we mean it, sometimes we fall back. But Hashem says, “I forgave you. I forgave you.” You're clean.
And again, we have to act like this with our friends. Sometimes someone asks you forgiveness, and you forgive them. But is it really clean?
A great example of this Middah is the story with the Rav Moshe Feinstein. There was a man that was upset about a certain decision that Rav Moshe Feinstein made in Halacha. This man felt it was too liberal and he actually came out in a very disrespectful way against Rabbi Feinstein's decision. A few weeks or months later, this man needed a letter of approbation from Rabbi Feinstein for something. And he had the arrogance, so to say, to approach Rav Feinstein and ask for a letter- after he had done this disrespectful thing. Rav Feinstein happily gave him the approbation.
When the man left, Rav Feinstein's son said, “ Don’t you remember what this man did to you? Don't you remember what happened?”
To which Rav Feinstein answered,
“Of course I remember, but Yom Kippur passed already, and I forgave him.” This is very important. Sometimes we’ll forgive somebody, but that doesn't really mean that we, as we say, “forgive and forget,”’
But that is what V’Nakeh is, to forgive and forget. It's not in our minds anymore. It's a clean slate.
It’s a difficult challenge to really, truly forget what a person did to you and give them a clean slate and a new start, but that's what we want from God, so that's what we should do for others.