Hillula of Rabbi Shimon bar Yochai

Nachum Dov Brayer lighting a bonfire during the 2021 celebration

The most well-known custom of Lag BaOmer is the lighting of bonfires. The custom symbolises the "spiritual light" brought in to the world by Rabbi Shimon bar Yochai, to whom the Zohar is ascribed. At the tomb of Rabbi Shimon, the honour of lighting the main bonfire traditionally goes to the Rebbes of the Boyaner dynasty. This privilege was purchased by Rabbi Avrohom Yaakov Friedman of Sadigura from the Sephardi guardians of Meron and Safed. He bequeathed the honour to his eldest son, Rabbi Yitzchok Friedman of Boyan and his progeny.[6] The first hadlakah (lighting) is attended by hundreds of thousands of people annually; in 2001, the crowd was estimated at 300,000.[7] In 2018, 18 different Hassidic Rebbes took turns leading the festivities surrounded by their followers.[8]

An account published in 1848 describes how vast numbers of Jews would arrive at the tomb to celebrate the anniversary of Rabbi Shimon's death. It relates that over the tombs of each of the three rabbis buried in the compound was a cupola and a pillar about 3 ft high which had a hollow scooped out which would hold about 80 pints of oil each. The privilege to set the oil ablaze was sold to the highest bidder, who would use a "costly shawl or richly ornamented dress" to ignite it. "The Jews remain here for 3 days and nights, praying, and reading, and feasting. The money thus obtained, which amounts to a large sum, is employed to keep the building in repair."[9]

A custom observed during the Hillula is the free distribution of drinks. According to Taamei HaMinhagim, it is a segula (propitious practice) to distribute chai rotel (Hebrew: ח״י רוטל), a liquid measure of about 54 liters. The Hebrew word chai is the numerical equivalent of 18. Rotel is a liquid measure of about 3 liters. Thus, 18 rotels equals 54 liters (about 13 gallons). It is popularly believed that if one donates or offers 18 rotels of liquid refreshment (grape juice, wine, soda or even water) to those attending the celebrations at bar Yochai's tomb on Lag BaOmer, then the giver will be granted miraculous salvation.[10] This practice was endorsed by Rabbi Ovadia miBartenura[11] and The Shelah HaKadosh.[12] The Bobover Rebbe, Rabbi Ben Zion Halberstam, sent a letter from Poland to his Hasidim in Israel asking them to donate chai rotel in Meron on this holy day on behalf of a couple that did not have children.[12] Several local organizations solicit donations of chai rotel and hand out the drinks on the donor's behalf in Meron on Lag BaOmer. Nine months after Lag BaOmer, the Ohel Rashbi organization even invites couples who prayed at the tomb and had a child to come back to Meron to celebrate the births.[11]

A rabbi performs the traditional first haircut on a three-year-old boy in Meron on Lag Baomer 1970.

It is customary at the Meron celebrations, dating from the time of Rabbi Isaac Luria, that three-year-old boys be given their first haircuts (upsherin), while their parents distribute wine and sweets. Similar upsherin celebrations are simultaneously held in Jerusalem at the grave of Shimon Hatzaddik for Jerusalemites who cannot travel to Meron.[13]

In a tradition started in 1833, on the afternoon preceding Lag Baomer, a Torah scroll belonging to the descendants of Rabbi Shmuel Abu is carried on foot from their home in Safed to the tomb.[8]

Every year, many people are injured due to over-crowding. On 15 May 1911, a crowd of about 10,000 filled the compound. A railing of a nearby balcony collapsed with about 100 people falling from a height of roughly 7 metres (23 ft) to the ground, resulting in the deaths of 11 people and 40 injured.[21][22] On 30 April 2021, with about 100,000 people in attendance, a deadly crush occurred in which 45 people were killed and more than 150 injured.