But when Prajāpati Dakṣa saw that he was not properly generating all kinds of living entities, he approached a mountain near the Vindhya mountain range, and there he executed very difficult austerities.
Srimad Bhagavata Purana
श्रीमद्भागवतमहापुराणम्
मूल श्लोकः
तमबृंहितमालोक्य प्रजासर्गं प्रजापतिः । विन्ध्यपादानुपव्रज्य सोऽचरद्दुष्करं तपः
tamabṛṃhitamālokya prajāsargaṃ prajāpatiḥ | vindhyapādānupavrajya so'caradduṣkaraṃ tapaḥ
SB 6.4.20