The Vilna Gaon was a staunch opponent of the chasidic movement, yet shared the movement’s interest in kabbalah and is considered an important and unique kabbalist. In addition to his Zohar commentary, Yahel Ohr, he wrote an extensive commentary on Sifra DeTzniuta ("The Book of Concealment"), a brief section included in the Zohar considered one of its core sections. The Gra’s commentary on these chapters is similarly seen as essential to understanding his approach to Kabbalah. It is often published with an introduction by Rabbi Chaim of Volozhin, discussing the Gaon’s views on both the revealed Torah and the esoteric concepts hidden in Sifra DeTzniuta.