Adhyāya 166: Kṛtaghna-doṣa (कृतघ्नदोषः) — the fault of ingratitude and the limits of expiation
चरेयु: सर्व एवैते वीरहा यद् व्रतं चरेत् । चान्द्रायणं चरेन्मासं कृच्छूं वा पापशुद्धये
Bhīṣma said: All of them should, each for his own purification, observe the vow prescribed for a slayer of a hero (vīra-hā). Or, for the cleansing of sin, one should practice the Cāndrāyaṇa vow for a month, or else the Kṛcchra vow, to become purified of wrongdoing.
भीष्म उवाच