SB 6.4.20

tam abṛṁhitam ālokya
 prajā-sargaṁ prajāpatiḥ
vindhya-pādān upavrajya
 so ’carad duṣkaraṁ tapaḥ
Word for word: 
tam — that; abṛṁhitam — not increasing; ālokya — seeing; prajā-sargam — the creation of the living entities; prajāpatiḥ — Dakṣa, the generator of living entities; vindhya-pādān — the mountains near the Vindhya mountain range; upavrajya — going to; saḥ — he; acarat — executed; duṣkaram — very difficult; tapaḥ — austerities.
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.