By Rabbi Nuriel Zargari:
The gemara in Nedarim daf 9 tells that Shimon Hatsadik said in all my days only once have I eaten from a Korban of a Nazir, once a Nazir came from the south and I saw that he had beautiful eyes and was good looking with beautiful curly hair. I said to him, “my son, why did you see fit to destroy this beautiful hair of yours?” He replied to me, “I was a shepherd to my father in my town. Once I went to fill a pail with water from the spring, and I stared at my reflection in the water, then my Yetser Harah rushed over me and wanted to banish me from this world. I said to my Yetser Harah “’Rasha’ why are you acting with gavah in a world that is not yours, where your body is destined to be consumed by the worms, I swear that I will become a Nazir and shave for the sake of heaven.” When Shimon Hatsadik heard that, he immediately rose and kissed him on the head and he said ”my son may there be more Nazir’s like you in Klal Yisrael.”
Chazal use this as the classic Nazir. But what was so special about this Nazir that got Shimon Hatsadik so excited? The Darchi Mussar explains that many times a person does a great mitzvah but with it he has not the best of intensions, because he really wants the respect and the attention that comes along with it. For example, he stands in front of the whole community and gives a big donation to a Yeshiva. Although he has done a big mitzvah, it may not find favor in the eyes of Hashem, because he did it for his own kavod. On the other hand, somebody that does a small mitzvah, or he has a yetser harah to do something wrong and he overcomes that but he does it between him and Hashem – nobody knows about it and his kavana was only to give nachat to his creator. To Hashem that is worth a lot more, because although it’s small, it was leshem shamaim. That’s what Shimon Hatsadik saw in this Nazir seemingly a small action[to refrain from haircuts and wine for thirty days] but he did it to fight his yetser harah without the fanfare and publicity. He didn’t post it; it was just between him and Hashem. That is the type of Nazir that we refer to as a kadosh is small act is beloved to Hashem.