Śrīmad-Bhāgavatam · Text 7.1.36
Who is speaking and story frame
श्रीनारद उवाच
एकदा ब्रह्मण: पुत्रा विष्णुलोकं यदृच्छया ।
सनन्दनादयो जग्मुश्चरन्तो भुवनत्रयम् ॥ ३६ ॥
śrī-nārada uvāca
ekadā brahmaṇaḥ putrā
viṣṇu-lokaṁ yadṛcchayā
sanandanādayo jagmuś
caranto bhuvana-trayam
The great saint Nārada said: Once upon a time when the four sons of Lord Brahmā named Sanaka, Sanandana, Sanātana and Sanat-kumāra were wandering throughout the three worlds, they came by chance to Viṣṇuloka.
Read this verse on Vedabase.ioThis verse has no purport; its meaning is explained by the verses around it.