The present article reveals insufficiently studied aspects of Islamic Mysticism (Sufism) in Russia’s Volga-Ural region at the end of the 19th – beginning of the 20th century in the context of modernization in late imperial Russia. A special attention is paid to the analysis of the contribution made by pedagogue, Sufi and scholar Khalil Rahimov to moderate Muslim reformism. He led extramural polemic with outstanding Russian Muslim reformists on the ways of development of the Muslim community, the role of Islamic Mystical tradition (Sufism) in the life of Muslims. He criticized their religious and philosophical teachings and views on the issues of faith and reason, the adaptation of scientific achievements and cultural models of advanced countries. Khalil Rahimov believed that Muslim education, culture and society should be developed without undermining the foundations of religion. Alongside the research, the article provides a Russian annotated translation of excerpts from Khalil Rahimov’s book “Himayat al-awliya’ min ihanat al-agwiya’” [The Protection of the Saints from the abuse of erring men].