Srimad-Bhagavatam: Canto 5 - Chapter 1 - Verse 42
Sanskrit:
योऽन्तर्विस्तार एतेन ह्यलोकपरिमाणं च व्याख्यातं यद्बहिर्लोकालोकाचलात् । तत: परस्ताद्योगेश्वरगतिं विशुद्धामुदाहरन्ति ॥ ४२ ॥
ITRANS:
yo ’ntar-vistāra etena hy aloka-parimāṇaṁ ca vyākhyātaṁ yad bahir lokālokācalāt; tataḥ parastād yogeśvara-gatiṁ viśuddhām udāharanti.
Translation:
My dear King, outside Lokāloka Mountain is the tract of land known as Aloka-varṣa, which extends for the same breadth as the area within the mountain — in other words, 125,000,000 yojanas [one billion miles]. Beyond Aloka-varṣa is the destination of those who aspire for liberation from the material world. It is beyond the jurisdiction of the material modes of nature, and therefore it is completely pure. Lord Kṛṣṇa took Arjuna through this place to bring back the sons of the brāhmaṇa.