The works of Ādi Śaṅkarācārya

Chāndogyopaniṣadbhāṣyam

Verse 75

सर्वास्वप्सु पञ्चविधसामोपासीत मेघोयत्सप्लवते स हिंकारो यद्वर्षति स प्रस्तावो याः प्राच्य स्यन्दन्ते स उद्गीथो याःप्रतीच्य स प्रतिहारः समुद्रो निधनम् ॥

In plain words

In all waters should one meditate upon the fivefold sāman: when the cloud gathers above, that is the hiṃkāra; when it pours down rain, that is the prastāva; the waters that flow to the east are the udgītha; those that flow to the west are the pratihāra; and the ocean is the concluding nidhanam.

Close to the Sanskrit

In all waters one should meditate upon the fivefold sāman: when the cloud gathers, that is the hiṃkāra; when it rains, that is the prastāva; which [rivers] flow eastward, that is the udgītha; which flow westward, that is the pratihāra; the ocean is the nidhanam.