Srimad-Bhagavatam: Canto 6 - Chapter 1 - Verse 20
Sanskrit:
तमबृंहितमालोक्य प्रजासर्गं प्रजापति: ।विन्ध्यपादानुपव्रज्य सोऽचरद्दुष्करं तप: ॥ २० ॥
ITRANS:
tam abṛṁhitam ālokyaprajā-sargaṁ prajāpatiḥvindhya-pādān upavrajyaso ’carad duṣkaraṁ tapaḥ
Translation:
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.