गोविन्द भाष्य (श्रील बलदेव विद्याभूषण - अचिन्त्यभेदाभेद वेदान्त ब्रह्मसूत्र भाष्य सटीक)

If (one says that the Brahman described in the Vedas is) Saguṇa Brahman (a
manifestation of the modes of material nature, and not the original Supreme Lord
Himself), Then I say this cannot be true, because Brahman is described in the
Vedas as "Atma" (the Supreme Self).
Purport by Śrīla Baladeva Vidyābhūṣaṇa
The Brahman described in the Vedas is not merely a saguṇa manifestation of the
mode of Goodness. Why? Because the Vedas use the word ātmā (the Supreme Self)
to describe Him. For example:
ātmaivedam agra āsīt puruṣa-vidhaḥ
"The Supreme Self (ātmā), who is a transcendental person, existed before this
material world was manifested in the beginning."
—Vājasaneya-saṁhitā
ātmā vā idam eka evāgra āsīt nānyat kiñcana
miṣat sa īkṣata lokān nu sṛja
"Before the material world was manifest, the Supreme Self (ātmā) alone existed.
Nothing else was manifested at that time. The Supreme Self then thought, `Let me
create the material planets.'"
—Aitareya Āraṇyaka
Both these texts clearly refer to the Supreme Self (ātmā) who existed before the
creation of the material world. Also, In the commentary on sūtra 1.1.2, I have
already explained that the word ātmā primarily refers to the perfect Supreme
Brahman, and not to anyone or anything else. For this reason the word ātmā used
in the scriptures should be understood to refer to the transcendental Supreme
Personality of Godhead, and not to any material manifestation of the mode of
goodness. The transcendental Supreme Person is described in the following
statements of Vedic literature:
vadanti tat tattva-vidas

• tattvaṁ yaj jñānam advayam*
  brahmeti pāramātmeti
• bhagavān iti śabdyate*