Namaste,
In the recently completed Vedanta Retreat at Rishikesh I had classes on the Paingala Upanishad. Some highlights of this Upanishad
1. One of the 108 Upanishads listed in the Muktikopanishad (59th) and one of the 22 SAmAnya Upanishads. Part of Shukla Yajur Veda and Atharva Veda.
2. It is in the form of a SamvAda between Paingala (student) and YAjnavalkya (Guru).
3. Covers all the Prakriyas like kArana-kArya, avasthA-traya, panchakosha etc. Explicitly talks about Pancheekaranam. Equates Anandmayakosha to svarupa-ajnAna and kArana-Shareera - स्वरूपाज्ञानमानन्दमयकोशः । तत्कारणशरीरम् ॥ Mentions ajAna as avyakta-lesha thereby equating maya and ajnAna and mentions jIva is covered by ajAna - अव्यक्तलेशाज्ञानाच्छादितपारमार्थिकजीवस्य
4. Scholars say Adi Shankara refers to it in his bhasya on Brahma Sutras but I am not able to locate the exact quote in the Bhashya
5. Defines Shravana, Manana, NididhyAsanam and Samadhi. Mentions Jivanmukti and Videhamukti
6. Describes the JnAni as a Jivanmukta who continues in the body till prarabdha ends and talks about the lakshanas of a jnAni .Even talks about the absence of any aparakarma for a jnAni after the fall of the body
7. Explicitly mentions AdhyAropa-ApavAda as the method to know the atma-svarupa अध्यारोपापवादतः स्वरूपं निश्चयीकर्तुं शक्यते ।
8. Vidyaranya's Panchadashi Chapter 1 seems like a summary of this Upanishad. Vidyaranya has quoted many vakyas from this Upanishad in this Chapter called Tattvavivekaprakarana
Those who are interested can listen to the below Playlist in YouTubehttps://
www.youtube.com/playlist?list=PLnZ7wsx5fCtVJcsImC8_m-RnGF-fXZV5wwith love and prayers,
Jaishankar