प्रतिग्रहभेदः — The Distinction between Giving and Accepting
Vṛṣādarbhī–Saptarṣi Dialogue
चाण्डालश्वपचौ वर्ज्यौ निवापे समुपस्थिते | काषायवासा: कुछ्ठी वा पतितो ब्रह्म॒हापि वा
bhīṣma uvāca | cāṇḍālaśvapacau varjyau nivāpe samupasthite | kāṣāyavāsāḥ kuṣṭhī vā patito brahmahāpi vā |
Bhishma said: When the time for offering the funeral rice-balls (piṇḍa) has arrived, one should keep away from that place the Caṇḍāla and the dog-cooker (śvapaca). Likewise, at the time of śrāddha, the learned prescribe that those such as a renunciant wearing ochre robes, a leper, a fallen person, or even a slayer of a brāhmaṇa should be removed from the vicinity, so that the rite is performed without ritual obstruction and with due purity according to the rule.
भीष्म उवाच
The verse states a dharmaśāstra-style rule for ancestral rites: when performing nivāpa/piṇḍa and śrāddha, certain persons considered ritually obstructive (by traditional norms) should be kept away so the rite proceeds with prescribed purity and focus.
In Anuśāsana Parva, Bhīṣma instructs Yudhiṣṭhira on dharma, including detailed conduct for śrāddha and offerings to ancestors. Here he specifies who should be excluded from the ritual space at the time of the offering.