"Tsugen Jakurei (1322-1391), whose teaching was most widely inherited in the Soto sect, is famous for his 'pit of burying-alive'. When an itinerant priest came to him in order to receive training, it was said, he tested the newcomer and if he perceived in the latter any impurity of motivation, he then simply threw him down into the pit."
January 1, 1970
https://en.wikiquote.org/wiki/Tsugen_Jakurei