Śrāddha-kalpa: Amarakantaka–Tīrtha-Māhātmya and Akṣaya Pitṛ-Tarpaṇa
यत्र वर्षसहस्राणि प्रयुतान्यर्बुदानि च / तपः सुदुश्चरं तेपे भगवानङ्गिराः पुरा
yatra varṣasahasrāṇi prayutānyarbudāni ca / tapaḥ suduścaraṃ tepe bhagavānaṅgirāḥ purā
There, in ancient times, the venerable Aṅgirā performed an exceedingly arduous austerity for thousands of years—through spans of prayuta and arbuda.