It is impossible for anyone to completely keep the 10 commandments. Do you or anyone you know keep them completely? Have you ever felt anger towards your brother? Have you ever lusted (ever)?
The text you referenced is not talking about keeping the commandments perfectly or not sinning, but suffering for Christ.
2 Peter 1"20But how is it to your credit if you receive a beating for doing wrong and endure it? But if you suffer for doing good and you endure it, this is commendable before God. 21To this you were called, because Christ suffered for you, leaving you an example, that you should follow in his steps.
22"He committed no sin,
and no deceit was found in his mouth."[
e] 23When they hurled their insults at him, he did not retaliate; when he suffered, he made no threats. Instead, he entrusted himself to him who judges justly.
24He himself bore our sins in his body on the tree, so that we might die to sins and live for righteousness; by his wounds you have been healed."
We are dead to sins and alive to righteousness. We are sinless by only accepting His sinless life as our own.
Who do you know who has ever kept the law perfectly? Jesus has made us more than conquerors over sin. We have the victory over sin. The law brings death, not life. When you focus on the law you will always fall short.
Galatians 3 "
19 What purpose then
does the law
serve? It was added because of transgressions, till the Seed should come to whom the promise was made;
and it was appointed through angels by the hand of a mediator. 20 Now a mediator does not
mediate for one
only, but God is one.
21
Is the law then against the promises of God? Certainly not! For if there had been a law given which could have given life, truly righteousness would have been by the law. 22 But the Scripture has confined all under sin, that the promise by faith in Jesus Christ might be given to those who believe. 23 But before faith came, we were kept under guard by the law, kept for the faith which would afterward be revealed. 24 Therefore the law was our tutor
to bring us to Christ, that we might be justified by faith. 25 But after faith has come, we are no longer under a tutor."
Romans 7 "6But now we are discharged from the Law and have terminated all intercourse with it, having died to what once restrained and held us captive. So now we serve not under [obedience to] the old code of written regulations, but [under obedience to the promptings] of the Spirit in newness [of life]."
Either way "wash their robes" or "keep commandments" it doesn't matter. What we define the commandments to be are different anyway.