Dhammapada 2.3.p11

2.3.p11

‘‘Moho rajo na ca pana reṇu vuccati,
Mohassetaṃ adhivacanaṃ rajoti;
Etaṃ rajaṃ vippajahitva bhikkhavo,
Viharanti te vigatarajassa sāsane’’ti. (mahāni. 209);

Delusion, not dirt, is properly called impurity; to delusion is correctly applied the term “impurity.”
Monks should rid themselves of this form of impurity and live faithful to the religion of him who is devoid of delusion.