CHAPTER THREE: SADHANA ADHYAYA
Section 3: Vedhadyadhikaranam: Topic 14 (Sutra 25)

Unconnected Mantras and sacrifices mentioned in certain Upanishads do not belong to Brahma-Vidya.
Vedhadyarthabhedat III.3.25 (384)
Because the matter (of certain Mantras) such as piercing and so on is different (from the matter of the approximate Vidyas), (the former are not to be combined with the latter).
Vedhadi: piercing etc.; Arthabhedat: because they have a different meaning.
Certain expressions occurring at the beginning of an Upanishad of the Atharva-Veda are taken up for discussion.
At the beginning of the Upanishad of the Atharvanikas we have "Pierce the whole (body of the enemy), pierce his heart, crush his veins, crush his head" etc. At the beginning of the Upanishad of the Tandins we have the Mantra "O God Savita! produce the sacrifice". At the beginning of Kathas and the Taittiriyaka we have "May Mitra be propitious to us and Varuna etc." At the beginning of that of the Kaushitakins we have "Brahman indeed is the Agnistoma, Brahman is that day; through Brahman they pass into Brahman, Immortality, those reach who observe that day."
The question is whether these Mantras and the sacrifices referred to in the Brahmanas in close proximity to the Upanishads are to be combined with the Vidyas prescribed by these Upanishads.
The opponent holds that they are to be combined, because the text exhibits them in proximity to the Upanishad-portions of the Brahmanas whose chief contents are formed by the Vidyas. In the case of Mantras we can always imagine some meaning which connects them with the Vidyas. The first Mantra quoted glorifies the heart, because the heart is often represented in the Vidyas as abode of meditation. Therefore Mantras which glorify the heart may constitute subordinate members of those Vidyas.
This Sutra declares that they are not to be combined because their meaning is different, as they indicate acts of a sacrifice and so have no association or relationship with the Vidyas.
The Mantras might be so employed if their whole contents were glorification of the heart, but this is not the case. The Mantra first quoted clearly expresses enmity to somebody and is therefore not to be connected with the Vidyas of the Upanishads, but with some ceremony meant to destroy one's enemy.
Other Mantras are subordinate to certain sacrificial actions. They cannot, because they occur in the Upanishads, be connected with the Vidyas on the ground of mere proximity.
For this reason the mentioned Mantras and acts are not on the ground of mere textual collocation to be viewed as supplementary to the Vidyas of the Upanishads.