Maaseh Rav (“The Story/Practice of the Rabbi”) is a work detailing the personal legal practices and customs of the 18th-century rabbinic leader, the Vilna Gaon (Rabbi Eliyahu ben Shlomo Zalman, also referred to as the “Gra”), written by his student, Rabbi Sa’adya and edited by Rabbi Yissachar Dov Ber ben Tanchum. The work is considered a most reliable source of the Gaon’s legal opinions, and is quoted in later works like the Mishnah Berurah. It has been printed in dozens of editions.