Charak Samhita
ते ह्यत्यन्तविरुद्धत्वादश्मनो भेदनाः परम्। लोके दृष्टास्ततस्तेषां प्रयोगःप्रतिषिध्यते ॥६३॥
Horse gram, due to exceedingly contradictory nature, breaks the stones as seen in the practice that is why its use is contraindicated.
english translation
te hyatyantaviruddhatvAdazmano bhedanAH param। loke dRSTAstatasteSAM prayogaHpratiSidhyate ॥63॥
hk transliteration by Sanscript