Srimad-Bhagavatam: Canto 3 - Chapter 1 - Verse 12

Sanskrit:

ब्रह्मोवाचमानसा मे सुता युष्मत्पूर्वजा: सनकादय: ।चेरुर्विहायसा लोकाल्लोकेषु विगतस्पृहा: ॥ १२ ॥

ITRANS:

brahmovācamānasā me sutā yuṣmat-pūrvajāḥ sanakādayaḥcerur vihāyasā lokāllokeṣu vigata-spṛhāḥ

Translation:

Lord Brahmā said: My four sons Sanaka, Sanātana, Sanandana and Sanat-kumāra, who were born from my mind, are your predecessors. Sometimes they travel throughout the material and spiritual skies without any definite desire.

Purport:

When we speak of desire we refer to desire for material sense gratification. Saintly persons like Sanaka, Sanātana, Sanandana and Sanat-kumāra have no material desire, but sometimes they travel all over the universe, out of their own accord, to preach devotional service.