Srimad Bhagavatam Canto 05, Chapter 20, Text 42

SB 5.20.42

yo ’ntar-vistara etena hy aloka-parimanam ca vyakhyatam yad bahir lokalokacalat; tatah parastad
yogesvara-gatim visuddham udaharanti.
 
Translation by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada: 
 
My dear King, outside Lokaloka Mountain is the tract of land known as Aloka-varsa, which extends for the same breadth as the area within the mountain — in other words, 125,000,000 yojanas [one billion miles]. Beyond Aloka-varsa 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 Krsna took Arjuna through this place to bring back the sons of the brahmana.
Srimad Bhagavatam Canto 05, Chapter 20, Text 41
Srimad Bhagavatam Canto 05, Chapter 20, Text 43