SB 3.15.12
brahmovaca
manasa me suta yusmat-
purvajah sanakadayah
cerur vihayasa lokal
lokesu vigata-sprhah
Translation by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada:
Lord Brahma said: My four sons Sanaka, Sanatana, Sanandana and Sanat-kumara, who were born from my mind, are your predecessors. Sometimes they travel throughout the material and spiritual skies without any definite desire.
Purport by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada:
When we speak of desire we refer to desire for material sense gratification. Saintly persons like Sanaka, Sanatana, Sanandana and Sanat-kumara have no material desire, but sometimes they travel all over the universe, out of their own accord, to preach devotional service.