Chappāṇakopamasutta
“Seyyathāpi, bhikkhave, puriso arugatto pakkagatto saravanaṁ paviseyya. Tassa kusakaṇṭakā ceva pāde vijjheyyuṁ, sarapattāni ca gattāni vilekheyyuṁ. Evañhi so, bhikkhave, puriso bhiyyoso mattāya tatonidānaṁ dukkhaṁ domanassaṁ paṭisaṁvediyetha. Evameva kho, bhikkhave, idhekacco bhikkhu gāmagato vā araññagato vā labhati vattāraṁ: ‘ayañca so āyasmā evaṅkārī evaṁsamācāro asucigāmakaṇṭako’ti. Taṁ kaṇṭakoti iti viditvā saṁvaro ca asaṁvaro ca veditabbo.
The Simile of Six Animals
“Mendicants, suppose a person with wounded and festering limbs was to enter a thicket of reeds. The kusa thorns would pierce their feet, and the reed leaves would scratch their limbs. And that would cause that person to experience even more pain and distress. In the same way, some mendicant goes to a village or a wilderness and gets scolded, ‘This venerable, acting like this, behaving like this, is a filthy village thorn.’ Understanding that they’re a thorn, they should understand restraint and lack of restraint.