"Bar Yochai" (Hebrew: בַּר יוֹחַאי‎) is a kabbalistic piyyut (poem or hymn) extolling the spiritual attainments of Rabbi Simeon bar Yochai, the purported author of the preeminent kabbalistic work, the Zohar. Composed in the 16th century by Rabbi Shimon Lavi, a Sephardi Hakham and kabbalist in Tripoli, Libya, it is the most prominent and popular kabbalistic hymn, being sung by Jewish communities around the world. The hymn is sung by Sephardi and Ashkenazi Jews alike on Lag BaOmer, the Yom Hillula (anniversary of death) of bar Yochai, and is also sung during synagogue services and at the Shabbat evening meal by certain groups. Incorporating expressions from the Tanakh, rabbinical commentaries, and the Zohar, the hymn displays its author's own mastery of Torah and kabbalah.