Cintīsutta
“Tīṇimāni, bhikkhave, bālassa bālalakkhaṇāni bālanimittāni bālāpadānāni. Katamāni tīṇi? Idha, bhikkhave, bālo duccintitacintī ca hoti dubbhāsitabhāsī ca dukkaṭakammakārī ca. No cedaṁ, bhikkhave, bālo duccintitacintī ca abhavissa dubbhāsitabhāsī ca dukkaṭakammakārī ca, kena naṁ paṇḍitā jāneyyuṁ: ‘bālo ayaṁ bhavaṁ asappuriso’ti? Yasmā ca kho, bhikkhave, bālo duccintitacintī ca hoti dubbhāsitabhāsī ca dukkaṭakammakārī ca tasmā naṁ paṇḍitā jānanti: ‘bālo ayaṁ bhavaṁ asappuriso’ti. Imāni kho, bhikkhave, tīṇi bālassa bālalakkhaṇāni bālanimittāni bālāpadānāni.
Thinking
“There are these three characteristics, signs, and manifestations of a fool. What three? A fool thinks poorly, speaks poorly, and acts poorly. If a fool didn’t think poorly, speak poorly, and act poorly, then how would the astute know of them: ‘This worthy one is a fool, an untrue person’? But since a fool does think poorly, speak poorly, and act poorly, then the astute do know of them: ‘This worthy one is a fool, an untrue person’. These are the three characteristics, signs, and manifestations of a fool.