ऊने षष्ठमंशं दद्यात् ॥ कZ_०४.१.५३ ॥
ūne ṣaṣṭhamaṃśaṃ dadyāt
If it is below that (threshold), one should give a sixth share (as the applicable reward).
Together they form a graduated regime: very large hoards revert to the state; smaller hoards trigger a defined reward share to encourage disclosure.