Mahabharata 13.82.44

य इदं कथयेन्नित्यं ब्राह्मणेभ्यः समाहितःहव्यकव्येषु यज्ञेषु पितृकार्येषु चैव हसार्वकामिकमक्षय्यं पितॄंस्तस्योपतिष्ठति

ya idaṃ kathayennityaṃ brāhmaṇebhyaḥ samāhitaḥhavyakavyeṣu yajñeṣu pitṛkāryeṣu caiva hasārvakāmikamakṣayyaṃ pitṝṃstasyopatiṣṭhati

Our plain-language meaning of this verse is waiting for scholar review.