अग्निनिचयः (Agninichaya) / The Accumulation of Sacred Fire & the Classification of Pitṛs by Time-Order
तस्मादेते हि पितर आर्तवा इति नः श्रुतम् / मन्वन्तरेष्विह त्वेते स्थिताः कालभिमानिनः
tasmādete hi pitara ārtavā iti naḥ śrutam / manvantareṣviha tvete sthitāḥ kālabhimāninaḥ
Therefore we have heard that these Pitṛs are called the Ārtavas; through the Manvantaras they abide here, bearing the authority of Kāla, Time.