Vaisesika Sūtra 5.1.02

तथा हस्तसंयोगाच्च मुसले कर्म ॥२॥

tathā hastasaṁyogāc ca musale karma ॥2॥

[तथा (tathā) - likewise; हस्त-संयोगात् (hasta-saṁyogāt) - from conjunction with the hand; च (ca) - and; मुसले (musale) - in the pestle; कर्म (karma) - action;]

Likewise, action in the pestle arises from conjunction with the hand.