Ramayana
चिरात्सुमाली व्यचरद्रसातलं स राक्षसो विष्णुभयार्दितस्तदा । पुत्रैश्च पौत्रैश्च समन्वितो बली ततस्तु लङ्कामवसद्धनेश्वरः ॥ 7-8-29 ॥
For a long time that Rakshasa Sumali, tormented by fear of Vishnu, wandered in the netherworld of Rasatala; then the mighty lord of wealth (Kubera), accompanied by his sons and grandsons, came to dwell in Lanka.
english translation