Śaṅkaraon Brahma Sūtra 3.3.4

The Veda also declares the identity of the vidyAs; for all Veddnta-texts represent the object of knowledge as one cp. e.g. KL Up- I, 2, 15, ‘That word which all the Vedas record ;* Ait. Ar. Ill, 2, 3, 12, ‘Him only the BahvnlSas con- sider in the great hymn, the Adhvaryus in the sacrificial fire, the -S’/^andogas in the Mahdvrata ceremony.*—To quote some other instances proving the unity of the vidyAs : KL Up. I, 6, 2, mentions as one of the Lord’s qualities that he Ill ADHVAYA, 3 PADA, 5 . I9I causes fear; now this very same quality is referred to in the Taitt. Up. II, 7, in order to intimate disapprobation of those who are opposed to the absolute unity of that which is, * For if he makes but the smallest distinction in it (the Self), there is fear for him. But that fear is only for him who knows (a difference) and does not know (the oneness).’ —Similarly the Vai^anara, who in the Va^saneyaka is imaginatively represented as a span long, is referred to in the A^Mndogya as something well known, ‘But he who worships that Vabvdnara Self which is a span long,’ &c. {Kh, Up. V, 18, i). And as, on the ground of all Ved^nta-texts intimating the same matters, hymns and the like which are enjoined in one place are employed in other places (where they are not expressly enjoined) for the purposes of devout meditation, it follows that all Ved&nta-texts intimate also (identical) devout meditations.