The Ari Hakadosh was studying with his students. One of his young students entered and came to discuss something with his Rebbi the Ari Hakadosh. It was Rabbi Shmuel Azidah, later the author of Midrash Shmuel on Pirkei Avos. The Ari Hakadosh stood up in honor of his student and called out, "Boruch Habba." He took Rabbi Shmuel aside and spent a long time talking to him.
The other students were amazed. They couldn't understand why their Rebbi had stood up in honor of one of the younger students. Afterwards Rabbi Chaim Vital went up to his Rebbi and said, "Rebbi, I cannot hold back and I have to ask the Rebbi, what was so special that Rabbi Shmuel received such honor, something the Rebbi has never done in the past?"
The Ari Hakadosh replied, "you should know that I never stood up for Rabbi Shmuel, nor did I say Boruch Habba to him. When he walked in, he was accompanied by the holy Tanna Rabbi Pinchas ben Yair who was above his head, and it was to him I said Boruch Habba. And the reason Rabbi Pinchas ben Yair accompanied him is because he did a Mitzva today that Rabbi Pinchas ben Yair used to do regularly in his lifetime."
The Ari Hakadosh went on to explain the depth behind the words of Chazal that say 'Habo Litaher Mesa'ayin Oisoi' someone who comes to purify himself and better his behavior he is helped from Heaven. This means that when a person wants to do a Mitzva, then a Tzaddik or Tzaddikim that in their lifetime focused and searched after this Mitzva, their Neshama comes down and joins the person doing the Mitzva. And it is with their help we can succeed in fulfilling the Mitzva. Without their help the Yetzer Harah would entice us not to do the Mitzva and we wouldn't have the power to fight.
Rabbi Chaim Vital was even more curious now. So, he went out looking for Rabbi Shmuel and asked him, "please tell me what Mitzva you did today?"
Rabbi Shmuel replied, "This morning I got up early and I went to Shul. On my way I heard terrible crying. I decided to check it out. So, I followed the noise and entered the home. There I saw a whole family without any clothes on crying bitterly. They told me that robbers had broken into their home and taken everything from them. They had even forcibly taken their clothing they were wearing. So, I took off my outer clothing and gave it to the father and I went home and put on my Shabbos clothes, as you can see I am wearing my Shabbos clothes."
Rabbi Chaim Vital kissed him and went back to the Ari Hakadosh and told him the story. The Ari Hakadosh replied, "Rabbi Pinchas ben Yair used to do Pidyon Shevuyim (redeeming people who were kidnapped) and help poor and broken people. That is why he came down to join Rabbi Shmuel."
Reprinted from the Parshas Ki Savo 5785 email of Inspired by a Story by Rabbi Dovid Caro.