Aśauca-vidhi (Rules of Impurity) within Śrāddha-kalpa — Chapter on Testing/Selecting Brahmanas and Honoring the Atithi
उग्रेण तपसा युक्ता बहुज्ञाश्चित्रवादिनः / निन्दन्ति च द्विजातिभ्यः सर्वे ते पङ्क्तिदूषकाः
ugreṇa tapasā yuktā bahujñāścitravādinaḥ / nindanti ca dvijātibhyaḥ sarve te paṅktidūṣakāḥ
Those engaged in terrible penances, those who speak strangely despite possessing much knowledge, and those who revile the twice-born—all these are defilers of the row.