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

The Taittirīya Upaniṣad (2.6.1) explains:
so 'kāmayata bahu syāṁ prajāyeya sa tapo 'tapyata tapas taptvā idaṁ sarvam asṛjat.
yad idaṁ kiñcana tat sṛṣṭvā tad evānuprāviśat. tad anupraviśya sac ca tyac
cābhavat.
"He desired: I will become many. I will father many children. He performed
austerities and created everything. Then He entered within the world He had
created. After He entered He became all that is manifest and all that is unmanifest."
Because it is here taught that by His own desire He resides as Paramātmā within
all conscious living entities and unconscious matter, and because it is also taught
here that he is the creator of everything, it must be concluded that He is both the
ingredient of the which the creation is made and the original creator and as well.
Sūtra 25
sākṣāc cobhayāmnānāt
sākṣāt -directly; ca-certainly; ubhaya-both; āmnānāt-because of direct
statement.
(Brahman is both creator and the ingredient of creation) because both (truths)
are directly stated (in the scriptures).
Purport by Śrīla Baladeva Vidyābhūṣaṇa
The word ca here means "certainly." The Taittirīya Brāhmaṇa (2.8.9.6)
explains:
kiṁsvid vanaṁ ka u sa vṛkṣa āsīt
yato dyāvā-pṛthivī niṣṭatakṣuḥ
manīṣiṇo manasā pṛcchataitat
yad adhyatiṣṭhad bhuvanāni dhārayan
brahma vanaṁ brahma sa vṛkṣa āsīt
yato dyāvā-pṛthivī niṣṭatakṣuḥ
manīṣiṇo manasā prabravīmi
vo brahmādhyatiṣṭhad bhuvanāni dhārayan