प्रतिग्रहभेदः — The Distinction between Giving and Accepting
Vṛṣādarbhī–Saptarṣi Dialogue
संकीर्णयोनिर्विप्रश्न॒ सम्बन्धी पतितश्न यः । वर्जनीया बुधैरेते निवापे समुपस्थिते
saṅkīrṇayonir vipraśna-sambandhī patitaś ca yaḥ | varjanīyā budhair ete nivāpe samupasthite ||
Bhīṣma said: “A man of mixed or irregular birth, a relative connected with a vipraśna (one who violates or troubles the Brahminical order), and anyone who has fallen from right conduct—such persons are to be excluded by the wise when the time for the śrāddha offering (nivāpa/piṇḍadāna) has arrived.”
भीष्म उवाच
That śrāddha (ancestral offering) should be conducted with careful attention to ritual boundaries; those classified as ritually fallen or socially/ritually disruptive are to be kept away at the time of the offering.
In Anuśāsana Parva, Bhīṣma instructs Yudhiṣṭhira on dharma, including detailed conduct for śrāddha. Here he lists categories of persons whom the learned tradition considers to be excluded when the nivāpa/piṇḍa offering is about to be made.