Verse 2.595-596

Sanskrit text and transliteration:

यतो वाचो निवर्तन्ते तद्ब्रह्मेति प्रतीयताम् ॥ ५९५ ॥
शब्दप्रवृत्तिहेतूनां प्रत्यगात्मन्यसम्भवात् ।
शब्दार्थासम्भवं प्राह ह्यप्राप्येत्यादराच्छ्रुतिः ॥ ५९६ ॥

yato vāco nivartante tadbrahmeti pratīyatām || 595 ||
śabdapravṛttihetūnāṃ pratyagātmanyasambhavāt |
śabdārthāsambhavaṃ prāha hyaprāpyetyādarācchrutiḥ || 596 ||

English translation of verse 2.595-596:

That should be known as Brahman from which (all) words return. Since the features necessary for the usage of words for the purpose of denoting objects are absent in the inward Self, śruti carefully declares through the expression aprāpya that words do not denote it.

Notes:

The ninth anuvāka of the Upaniṣad is covered by verses (595) to (750).

Verses (595) to (599) explain the meaning of yato vāco nivartante aprāpya.

Brahman-Ātman from which all words along with the mind turn back without reaching it can be known only through śabda-pramāṇa. And yet śruti says that words along with the mind return without reaching Brahman-Ātman. Words are used to refer to a relation, or a quality, or an action, or the class characteristic, or the name of an object (ṣaṣṭḥī-guṇa-kriyā-jāti-rūḍhayaḥ śabdapravṛtti-hetavaḥ). But none of these factors which occasion the usage of words are present in the Self. It is for this reason that śruti says that words do not reach the Self. It means that Brahman-Ātman cannot be denoted by words.