When a person can be in Meron for Lag b'Omer, the potential for miracles and salvations increases.
Reb Ovadyah of Bartenura zt'l writes in a letter from Eretz Yisrael to Italy, "On the eighteenth of Iyar, the day of his [Reb Shimon's] yahrtzeit, people from all around Meron go to Meron and light bonfires... Many barren bear children, the ill are healed, because of the vows they take on at that place."
Obviously, Rav Bartunara's testimony is very trustworthy. In this letter, he discusses other miracles that people in Eretz Yisrael discuss, from other holy areas in Eretz Yisrael, and he debates them. He expresses that there is no proven evidence to their claims that miracles occurred there. However, when it comes to Meron, he discusses the miracles that happen there as a fact, and there is no doubt.
Year 5779, in Meron: After saying Tehillim and tefillos, someone made a kabbalah that he would study an entire volume of Zohar (edition Masuk m'Dvash, 720 pages) before the following year Lag b'Omer. (He told himself that he would try to understand the easier (נגלה) sections of the Zohar and he would just read the kabbalah sections.) This person had many debts, but that year (after he had gone through half the Zohar), money poured in from an unexpected source. He was able to cover his debts and more.
This is because when one makes a kabbalah, he becomes connected with Reb Shimon bar Yochai, becoming a vessel to receive the blessings.
We received the following letter:
"I want to tell my personal story, although it is very difficult for me to do so. I am a chassidishe yungerman. I work half of the day and learn in kollel the other half. A couple of years ago, at the workplace, I had very difficult tests in kedushah... I felt I was at the entrance of Gehinom, ready to fall in. On Lag b'Omer, 5779, I traveled to Meron. I felt empty, without yiras Shamayim, but I knew Reb Shimon is for everyone, even for people like me.
"In Meron, I heard divrei Torah about the importance of making a kabbalah tovah. At that moment, I made a kabbalah that until Rosh Hashanah, I would distance myself from the difficult test at the workplace. I did so and kept up my resolve after Rosh Hashanah. Now, two years later, I can say that it wasn't easy; there were tests, but I kept strong all this time. I just realized something interesting. My parnassah is always tight, but the last time I needed to borrow money was before Lag b'Omer, year 5779! From the time I made the kabbalah, I never had to borrow another penny. Also, in Shevat 5780, exactly nine months after Lag b'Omer, my wife gave birth to a healthy girl, and it was a natural birth, contrary to all the doctors’ predictions. I am certain that Hashem has helped me in other ways too, in the merit of my kabbalah tovah, only I don't recognize them all."
The Bartenura mentions that the miracles come from the vows that people make in Meron. The vows refer to the good kabbalos (such as giving tzedakah or taking on a good practice) that people accept on themselves when they are in Meron, on Lag b'Omer. It is sufficient to accept the kabbalah on oneself bli neder, without an actual vow.
Also, when Reb Shimon lived, he was known among the chachamim as the person to go to when one needs a salvation.
The Zohar (Rus 104) says:
There was an epidemic in Lud. People went around the city with Reb Shimon so that he could see with his own eyes their suffering.
Reb Shimon said, "How can it be that I’m in this city, and there’s a plague? I decree that the plague should stop!"
A bas kol came forth and spoke to the damaging angels, "You must leave this city. Reb Shimon bar Yochai is here. Hakadosh Baruch Hu decrees in heaven, and Reb Shimon annuls the decrees on earth."
In another location, the Zohar says that the world suddenly became dark. Reb Shimon bar Yochai told his son, Reb Elazar, "Come with me, and we will see what Hakadosh Baruch Hu is planning to do to the world."
They found a malach, tall like a high mountain, with thirty flames of fire coming out of its mouth. Reb Shimon asked the malach what it was planning to do. The malach replied, "It states (Bereishis 18:18) ואברהם יהיה היו, and יהיה is gematriya thirty. This means that in every generation, there must be at least thirty tzaddikim who are similar to Avraham Avinu. But now, there aren't thirty tzaddikim in the world like Avraham, so Hashem sent me to destroy the world."
Reb Shimon bar Yochai said to the malach, "Go to Hakadosh Baruch Hu and tell Him that Yochai's son is in the world."
