Venerable Phra Ajahn Sao Kantasilo Mahathera (1859–1942) was a monk in the Thai Forest Tradition of Theravada Buddhism. He was a member of the Dhammayuttika Nikaya. Ajahn Sao was ordained as a monk at the age of 20, entering the Maha Nikaya order. In 1887 he re-ordained in the Dhammayut order. Both ordinations were in Ubon Ratchathani Province. As a teacher, Ajahn Sao urged his disciples to be diligent, systematic and consistent. He taught them to wake at 3 a.m. and to practice sitting or walking meditation until 10 p.m.