Ahava raba ahavtanu, chemla gedola viysairah chamalta aleinu, ba'avur avoseinu shebatchu Becha vatelamdaim chukei chaim, kain techaneinu u'selamdainu..
"A great love You have loved us, a great and excessive compassion You have had mercy on us, for the sake of our forefathers who put their faith in You, and You taught them RULES OF LIFE, so may You grant us and teach us."

HaKadosh Baruch Hu has given us the Torah and through it, RULES OF LIFE.  This expression in the tefilla has always struck me.  It relays the message that if one properly learns and examines the teachings of the Torah, he will find not only the road map to Olam Habah, the world to come, but also all the traffic signals and maps guides how to steer around and deal with the twisting and meandering alleyways, streets and highways of Olam HaZeh, this world.

Lo sikom veloh sitor es bnei amecha.. Ani Hashem.
"Do not take revenge and do not bear a grudge against a member of your nation.. I am HaShem."

Rashi explains that lo sitor entails bearing animosity that does not get expressed in action but is harboured in the heart.

What is so bad about bearing a grudge?  After all, a person was wronged by someone else.  Is it not commendable that he takes no revenge, even though he was hurt by him??  What is he supposed to do? How is he supposed to deal with wrongdoing done to him by which he felt and perhaps actually was hurt?

The Chafetz Chaim zt"l gives the following mashal:

Shimon was searching for his friend Reuvain.  He was told that Reuvain was in a certain restaurant.  Shimon went to the restaurant and was told that he would find Reuvain at the grocery store.  Shimon then went to the grocery store and started to ask around for Reuvain.  "Is Reuvain here?  Are you Reuvain?"  "No," was the reply, "Reuvain isn't here."  Shimon then began to get angry and exasperated.  "Why are you not Reuvain??  Why is a single person here not Reuvain?!"
All the bystanders started to laugh.  Was it their fault that they were not the man for whom Shimon was searching?  Shimon certainly made a fool of himself.

So it is when a person expects a favour from someone and it does not materialize.  This is Heavenly sign that this person was not the worthy of doing him this favour.  He is simply not the right address through which this favour was to be done.  Thus, there is no reason to take revenge and not even to feel animosity.  Simply, this person was not chosen as the worthy one to do him this favour.

The Torah commands us not to take revenge and not even to bear a grudge, for these responses show a lack of faith in the fact that all situations are orchestrated by Hashem.  This is the connection between the beginning of the passuk and the conclusion, "Ani Hashem".  Everything in this world is directed by Hashem, we are only carrying out His Will, and therefore there is no place for feelings of revenge or animosity toward any mortal being.

Of course this is only looking at one side of the story.  It does not come to negate free will or to justify hardheartedness or cruel behaviour - "I'm only carrying out His will, that is why I'm being mean.".  Of course we must all strive and pray to be the ones that carry out meritous tasks and not chas veshalom otherwise.  Megalgelin zchus al yedai zakai vechovah al yedai chayav.

Rather, there is most important message to be learned from this mitzvah, a RULE OF LIFE.
In life a person encounters all kinds of behaviour, communal and individual, and not always is the behaviour of the group or of the individual ideal.  How do we respond to the way this behaviour affects us?  The natural response is to harbour bitterness and resentment.  What else are we supposed to do?  To smile back at those who chas veshalom hurt us?

Through the mitzvah of Lo sikom velo sitor .. Ani Hashem, we find the answer.  Do not focus your attention and energy on concentrating on the unjust and misbehaviour of others even if you are directly affected by it. The Torah forbids us to express bitterness in action towards the wrongdoer, in words to him and even the non expression of these negative feelings by  absorbing and carrying them around with us, expressed and directed at no one but ourselves.  Absorbing and carrying around bitterness is chas veshalom detrimental even to a person's health and greatly hampers a persons advancement in life.

So how are we to deal with such situations, when we are treated unfairly or chas veshalom hurt by other's misbehaviour?

The answer is:
ANI HASHEM.

The only positive, constructive solution to this dilemma is
ANI HASHEM.

Everything that happens to us, happens b'hashgacha pratis, and within every single occurrence in our lives is contained a hidden message from Above about the direction our lives should be taking.  When we go through negative encounters with others, we are not supposed to be apathetic!!! This certainly is not the meaning of the mitzvah.  Rather, we must use the experience as a springboard for moving in a positive direction for our own personal development.

This is a great challenge, a very tall order.  How is it implemented?

I once read an article which studied students' achievements. It contained the following most aptly stated conclusion:
Low achievers were outwardly oriented.
High achievers were inwardly oriented.
A person can go through life chas veshalom  getting nowhere, by concentrating his energies on what is going around him, on how people treat him and by allowing all this to direct him.  Thus he can have all the justified excuses in the world as to why he lands up where he is.

What does inward orientation mean to the Jew? Firstly, it requires a complete change of focus.  It requires a person to forget about others being the cause of any significant development in his life. Rather, it requires a person to draw deeply into his inner resources as an active response to anything he encounters, to access and express his tzelem Elokim, his Chelek Eloka Mima'al, the eternal spiritual resources of his neshama.  Most essential is developing Emunah and Bitachon. I don't know how this can be done without tefilla.  We have to be very aware of our goals  (even knowing our goals can be a goal!) and where we are in respect to them and express our needs accordingly in Tefilla.  For example, the person would like to move ahead, but is confused by the message and the direction the negative experience is supposed to lead him.  Or the person is aware what he is supposed to be doing with himself, but feels very weakened by other people's  behaviour or unable to shake off the bitterness.  Through tefilla a person communicates his deepest and most real and immediate questions and needs to HaKadosh Baruch Hu, and it is through tefilla that he receives his strength to struggle, his salvation.

Rav Aryeh Levine zt'l had dealings with a certain bank clerk who behaved in an especially rude and unfriendly manner toward him.  It was very frustrating, for as much as he tried to be friendly and polite. the clerk's rude behaviour continued.  Anyone familiar with the life story of R' Aryeh Levine can understand how out of character this encounter was, for Rav Aryeh, the "tzaddik from Yerushalayim" was known for his kindness and devotion to all.  Rav Aryeh, perplexed, turned for the answer in Tefilla.  It then hit him.  He remembered that there was once a certain financial misunderstanding between him and a certain bank (in a different country!), and it had not been rectified.  Rav Aryeh immediately took care of it.
"Mysteriously",  the rude behaviour of the clerk stopped.

In conclusion, the Torah instructs us, Lo sikom velo sitor.. Ani Hashem.  We must abandon our personal feelings of bitterness and animosity towards our fellow Jews, however justified we can rationalize away the emotions.  We must recognize that this is merely a low tactic of the Yetzer Harah, the evil inclination, who seeks to sap our energy and divert our attention and focus from the guidance of the Hashgacha Pratis in our lives.  By rebounding and converting negative energy into positive energy, this in itself is a vital part of discovering what is truly good, and who we really are.  For there is indeed great and wondrous bracha of fulfilment, achievement and happiness awaiting every single member of Klal Yisrael.

The Mai HaShiloach explains "Kedoshim tihiyu":
Kedoshim means mezumanim, prepared (as in hakdishu-prepare yourselves).
HaKadosh Baruch Hu commands Am Yisrael to always be prepared and waiting for Him to come to our rescue and to enlighten us with Torah.
Ki Kadosh Ani :
For I (Hashem) am always ready and prepared to help you, to save you, Am Yisrael.

May HaKadosh Baruch Hu grant us all the ability to take full advantage of all of our opportunities, b'siyata d'Shmaya, amen.

Chodesh tov umevorach.
A gutten erev Shabbos,
from Yerushalayim Ir HaKodesh