Wikipedia
The Kollyvades were the members of a movement in Eastern Orthodoxy that began in the second half of the eighteenth century among the monastic community of Mount Athos, which was concerned with the restoration of traditional practices and opposition to unwarranted innovations, and which turned unexpectedly into a movement of spiritual regeneration. As Bishop Kallistos of Diokleia succinctly points out:
The movement derived its name from the Kollyva (boiled wheat) which is used during memorial services. Its proponents were Athonite monks who adhered strictly to Holy Tradition, and insisted that memorial services should not be performed on Sundays, because that is the day of the Lord's Resurrection, but rather on Saturday, the usual day for the commemoration of the dead. They were also in favor of frequent reception of Holy Communion, and practiced unceasing prayer of the heart.
The terms “Kollyvades”, “Kollyvistai”, and “Sabbatianoi” were epithets which were originally meant sarcastically as bitter insults, however over the passage of time these contemptuous appellations became a title or badge of honor. The leaders of the movement were Neophytos Kafsokalyvitis (1713-1784), Saint Makarios (Notaras) of Corinth (1731-1805), Saint Nicodemus of the Holy Mountain (1749-1809), and Saint Athanasios Parios (1722-1813).