汚れた布がうまく染まらないという喩えを通じて、汚れを背負う心は幸福を見出せないと説き、真の浄化とは儀式的沐浴ではなく心の浄化であると述べる『中部』第七経。

The seventh sutta of the Majjhimanikāya, teaching through the simile of a dirty cloth that fails to take dye well that a heart burdened with impurities cannot find happiness, and describing true purification as cleansing of the heart rather than ritual bathing.