Sankaracarya's Vivekachudamani 394

क्रियासमभिहारेण यत्र नान्यदिति श्रुतिः ।

ब्रवीति द्वैतराहित्यं मिथ्याध्यासनिवृत्तये ॥

kriyāsamabhihāreṇa yatra nānyaditi śrutiḥ |

bravīti dvaitarāhityaṃ mithyādhyāsanivṛttaye ||

(Sankaracarya's Vivekachudamani 394)

With many predicates, Sruti declares the absence of duality with the phrase, 'where there is nothing else' etc., in order to remove all false superimposition.

Vedic literature are divided into two main categories:

Shruti – that which has been heard

Smriti – that which has been remembered

Shruti is canonical, consisting of revelation and unquestionable truth, and is considered eternal. It refers mainly to the Vedas themselves.

Smriti is supplementary and may change over time. It is authoritative only to the extent that it conforms to the bedrock of shruti.

Main shruti texts (3)

The Four Vedas

The 108 Upanishads

The Vedanta Sutra

Main smriti texts (4)

The Itihasas (histories or epics)

The Bhagavad-gita (philosophy)

The Puranas (stories and histories)

The Dharma Shastra (law books)

Other texts (4)

The Vedangas (limbs of the Vedas)

The Upavedas (following the Vedas)

Sectarian texts (e.g. agamas, tantras)

Vernacular literature

In the text above Sankaracarya explaining Brahman is the only Truth or he is the one and only God. The Brahman generally means the all-pervading, self-existent power. The concept of the Brahman was, for the most part, first developed in the Upanishads. There we begin to find descriptions from which our understanding of it grows. It is invisible, ungraspable, eternal, without qualities, and the imperishable source of all things. (Mundaka Upanishad 1.1.6-7)

Brahma is confirming who is the Brahman in Brahma Samhita Text 34:-

panthas tu koti-sata-vatsara-sampragamyo

vayor athapi manaso muni-pungavanam

so 'py asti yat-prapada-simny avicintya-tattve

govindam adi-purusam tam aham bhajami

I worship Govinda, the primeval Lord, only the tip of the toe of whose lotus feet is approached by the yogis who aspire after the transcendental and betake themselves to pranayama by drilling the respiration; or by the jnanins who try to search out the nondifferentiated Brahman by the process of elimination of the mundane extending over thousands of millions of years.