Verse 1.1.5

तत्रापरा ऋग्वेदो यजुर्वेदः सामवेदोऽथर्ववेदः शिक्षा कल्पो व्याकरणं निरुक्तं छन्दो ज्योतिषमिति ।
अथ परा यया तदक्षरमधिगम्यते ॥ ५ ॥

tatrāparā ṛgvedo yajurvedaḥ sāmavedo'tharvavedaḥ śikṣā kalpo vyākaraṇaṃ niruktaṃ chando jyotiṣamiti |
atha parā yayā tadakṣaramadhigamyate || 5 ||

5. Of these, the Apara is the Rig Veda, the Yajur Veda, the Sama Veda, and the Atharva Veda, the siksha, the code of rituals, grammar, nirukta, chhandas and astrology. Then the para is that by which the immortal is known.

Shankara’s Commentary:

Com.—Of these, what Apara vidya is, is explained. Rig Veda, Yajur Veda, Sama Veda, and the Atharva Veda, these four Vedas, the siksha, the code of rituals, grammar, nirukta, chhandas and astrology, these six angas (of Vedas), all this is knowledge called Apara; now, knowledge called Para is explained. It is that by which the “immortal” as hereafter described is reached; for, the root gam, with adhi before it, generally means reach. Nor is the attainment of the highest, different from the sense of knowledge. The attainment of the highest is merely the removal of ignorance. They mean the same thing. It may he asked how that Vidya could be called para and a help to emancipation, if such Vidya be excluded by the Rig Veda, etc; for, the Smriti says “Those Smritis which are excluded by the Vedas, etc.” It will become unacceptable, because it sees wrongly and leads to no good results; and again the Upanishads will become excluded by the Rig Veda, etc., but if they are included in the Rig Veda, etc., a separate classification is useless. How then can it be called para? The objection has no force; for by the term “Vidya” is here meant the knowledge of a subject; by the term “Para vidya” is meant primarily in this context, that knowledge of the immortal which could be known through the Upanishads and not the mere assemblage of words in them; but by the term vidya is always understood the assemblage of words forming it. As the immortal cannot be realised by a mere mastery of the assemblage of words without other efforts, such as the approaching a preceptor and spurning all desires, etc., the separate classification of the knowledge of Brahman and its designation as Para vidya are proper.