Mahabharata — Anushasana Parva, Shloka 12
अत्रेः तपोबलप्रकाशः तथा च्यवनस्य सोमाधिकारः
Atri’s Illumination by Tapas; Cyavana and Soma-Entitlement
कृष्णपक्षे तु यः श्राद्धं पितृणामश्नुते द्विज: । अन्नमेतदहोरात्रात् पूतो भवति ब्राह्मण:,जो द्विज कृष्णपक्षमें किये हुए पितृश्राद्धका अन्न भोजन करता है, वह एक दिन और एक रात बीत जानेपर शुद्ध होता है
kṛṣṇapakṣe tu yaḥ śrāddhaṃ pitṝṇām aśnute dvijaḥ | annam etad ahorātrāt pūto bhavati brāhmaṇaḥ ||
毗湿摩说道：“一位二次生者（dvija）若食用在黑半月（kṛṣṇa-pakṣa）所行、为祖灵设的施祖（śrāddha）供食，则须待一昼一夜圆满过去，方得复归清净。”此教诲表明：祭食具强大效力，亦受伦理戒律所摄——可参与而食，却带来暂时不净；待时日流转并依正法行持，便自消除。
भीष्य उवाच
Educational Q&A
Śrāddha-food, especially when connected with ancestral rites in the kṛṣṇapakṣa, is ritually sensitive: a qualified eater incurs a temporary impurity, but becomes purified after one full day and night, emphasizing regulated participation and time-bound purification in dharma.
Bhīṣma is instructing on dharma concerning śrāddha observances—specifically, the consequence and purification period for a dvija/brāhmaṇa who partakes of food offered to the ancestors during the dark fortnight.