समः क्ष्णुवः

The verb क्ष्णु 'to sharpen, whet, or grind,' is generally parasmaipadi, but it is atmanepadi, when it is preceded by the prefix सम्; as संक्ष्णुते शस्त्रम् 'he whets the weapon', संक्ष्णुवाते 'they two whet', संक्ष्णुवते 'they all whet.'

It might be objected, why has a separate aphorism been made of the verb kshnu, when it could well have been included in the sutra 1.3.29 ante, which also speaks of the force of the prefix sam, when used with the verbs gam, richchha, &c. To this the answer is that, that sutra treats of intransitive verbs, the word akarmaka being understood therein, while the present sutra, as is evident from the example we have given above, treats of transitive verbs.,