Aśauca-vidhi (Rules of Impurity) within Śrāddha-kalpa — Chapter on Testing/Selecting Brahmanas and Honoring the Atithi
तावदश्नन्ति पितरो यावदश्नन्ति वाग्यताः / दत्तं प्रतिग्रहो होमो भोजनं बलिरेव च
tāvadaśnanti pitaro yāvadaśnanti vāgyatāḥ / dattaṃ pratigraho homo bhojanaṃ balireva ca
The Pitṛs partake for as long as the speech-restrained ones partake; giving, receiving, homa, the meal, and the bali-offering—all these belong to the śrāddha.