The works of Ādi Śaṅkarācārya

Chāndogyopaniṣadbhāṣyam

Verse 102

त्रयी विद्या हिङ्कारस्त्रय इमे लोकाःस प्रस्तावोऽग्निर्वायुरादित्यः स उद्गीथोनक्षत्राणि वयासि मरीचयः स प्रति-हारः सर्पा गन्धर्वा पितरस्तन्निधनमेत-त्साम सर्वस्मिन्प्रोतम् ॥ १ ॥

In plain words

The threefold vedic knowledge is the hīṅkāra; these three worlds are the prastāva. Fire, wind, and sun form the udgītha. Stars, birds, and rays of light form the pratihāra. Serpents, gandharvas, and ancestors form the nidhana. This sāman is interwoven throughout the whole of existence.

Close to the Sanskrit

Triple knowledge is the hīṅkāra; these three worlds are the prastāva; Agni, Vāyu, Āditya—that is the udgītha; stars, birds, rays—that is the pratihāra; serpents, gandharvas, ancestors—that is the nidhana. This sāman is woven in all.