रुद्रपार्षद
The Rudra-parshadas are the attendants of Rudra, who take refuge in the space of the navel. At SB 3.6.29 Maitreya says: 'tArtIyena svabhAvena bhagavan nAbhim AshritAH / ubhayor antaraM vyoma ye rudra-pArShadAM gaNAH'. In SB 3.6.27-28 heaven was attained by sattva and earth by rajas; these hosts, by the third nature, that is by the share of tamas, stand in the space between the two. Rudra himself is an epithet of Shiva, so only the attendants are declared, as a group.
Śrīmad Bhāgavata Mahāpurāṇa 3.6.29 — Sanskrit Wikisource (pinned chapter page; Devanagari from the cross-validated transcription in validation/sanskrit_skandha3.json)
Maitreya says that by the third nature arose the hosts who take refuge in the space between the two, the navel, and who attend upon Rudra: 'tArtIyena svabhAvena bhagavan nAbhim AshritAH / ubhayor antaraM vyoma ye rudra-pArShadAM gaNAH' (SB 3.6.29).