至聖三者聖セルギイ大修道院
Following the death of his wife, he became a monk at the Trinity Lavra of St. Sergius and received the monastic name Seraphim. He was later appointed Father Superior and Archimandrite of the Monastery of Saint Euthymius in Suzdal, and then of the New Jerusalem Monastery in Moscow. In 1905 he was appointed Bishop of Sukhumi. In subsequent years he was appointed Bishop of Orel (1906–1908), Chişinău (1908–1912), Tver (1912–1917), and Warsaw (1918–1921). In 1928 he was appointed Metropolitan of Petrograd.