Pitṛgaṇa-Vibhāga (Classification of the Pitṛs) and the Śrāddha–Soma Nourishment Cycle
देवताभ्यः पितॄणां हि पूर्वमाप्यायनं स्मृतम् / न हि योग गतिः सूक्ष्मा पितॄणां न पितृक्षयः
devatābhyaḥ pitṝṇāṃ hi pūrvamāpyāyanaṃ smṛtam / na hi yoga gatiḥ sūkṣmā pitṝṇāṃ na pitṛkṣayaḥ
It is remembered that the Pitṛs are to be nourished and satisfied before the gods. The course of the Pitṛs is subtle, and there is no wasting away of the Pitṛs.