Manava Dharmashastra 1.37

1.37

yakṣādīnāṃ svarūpabhedaścetihāsādipramāṇaka eva, na pratyakṣādīnāmanyatamena pramāṇena paricchidyate | tatra vaiśravaṇānucarā yakṣāḥ | rakṣāṃsi vibhīṣaṇādayaḥ | tebhyaḥ krūratarāḥ piśācāḥ aśucimarudeśādivāsino, nikṛṣṭā yakṣarākṣasebhyaḥ | hiṃsrāstu sarva eva | chadmanā kecit prāṇināṃ jīvamākarṣantyadṛṣṭayā śaktyā vyādhīṃśca janayantītyaitihāsikā mantravādinaśca | gandharvā devānucarā gītanṛttapradhānāḥ | apsaraso devagaṇikā urvaśyādyāḥ | asurā devaśatravo vṛtravirocanahiraṇyākṣaprabhṛtayaḥ | nāgā vāsukitakṣakādayaḥ | sarpāḥ prasiddhāḥ | suparṇāḥ pakṣiviśeṣā garutmatprabhṛtayaḥ | pitaraḥ somapājyapādināmānaḥ svasthāne devavadvartante | teṣāṃ gaṇamasṛjan |

Medhātithi’s commentary (manubhāṣya):
The various forms of the Yakṣa and other beings here mentioned can be known only from the Itihāsas and such other sources; they cannot be known by any of the ordinary means of cognition, perception and the rest.—The ‘Yakṣas’ are the followers of Kuvera;—‘Rākṣasas,’ Bivīṣaṇa and others;—beings more cruel than these last are ‘Piśācas,’ who live in unclean places and in deserts, &c., and are inferior to Yakṣas and Rākṣasas; though all three are mischievous; by trickery they draw out the life of living beings, and by some invisible power they bring about diseases: so say persons knowing the Itihāsas (stories) and Mantra (Incantations).—‘Gandharvas,’ are those followers of the Gods whose chief work consists of singing and dancing;—‘Apsarases,’ the courtezans of the Gods, Urvaśī and the rest;—‘Asuras,’ the Gods’ enemies, Vṛttra, Virocana, Hiraṇyāksa and so forth;—‘Nāgas’ (the Great Serpents), Vāsuki, Takṣaka and the rest;—‘Sarpas’ (Serpents) are well known;—‘Suparnas,’ the great Birds, Garuḍa and the rest;—‘Pitṛs,’ named ‘Somapa,’ ‘Ayyapa’ and so forth, who reside, like Gods, in their own regions; the ‘several orders’ of these also;—all these (the mighty sages) called into being.—(37)