SB 4.22.48
maitreya uvaca
ta atma-yoga-pataya
adi-rajena pujitah
silam tadiyam samsantah
khe ’bhavan misatam nrnam
Translation by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada:
The great sage Maitreya continued: Being thus worshiped by Maharaja Prthu, the four Kumaras, who were masters of devotional service, became very pleased. Indeed, they appeared in the sky and praised the character of the King, and everyone observed them.
Purport by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada:
It is said that the demigods never touch the surface of the earth. They walk and travel in space only. Like the great sage Narada, the Kumaras do not require any machine to travel in space. There are also residents of Siddhaloka who can travel in space without machines. Since they can go from one planet to another, they are called siddhas — that is to say, they have acquired all mystic and yogic powers. Such great saintly persons who have attained complete perfection in mystic yoga are not visible in this age on earth because humanity is not worthy of their presence. The Kumaras, however, praised the characteristics of Maharaja Prthu and his great devotional attitude and humility. The Kumaras were greatly satisfied by King Prthu’s method of worship. It was by the grace of Maharaja Prthu that the common citizens in his domain could see the Kumaras flying in outer space.