Viyahapannatti 6.7.308

6.7.308

sattheṇa sutikkheṇa vi, chettuṃ bhettuṃ va jaṃ kira na sakkā |
taṃ paramāṇuṃ siddhā, vadaṃti ādiṃ pamāṇāṇaṃ ||

That which, indeed, cannot be cut or cleaved even by the sharpest weapon,
that atom (paramāṇu), the liberated souls [and omniscients] declare to be the origin of measures.