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SB 10.3.24

śrī-devaky uvāca
rūpaṁ yat tat prāhur avyaktam ādyaṁ
 brahma jyotir nirguṇaṁ nirvikāram
sattā-mātraṁ nirviśeṣaṁ nirīhaṁ
 sa tvaṁ sākṣād viṣṇur adhyātma-dīpaḥ
Synonyms: 
śrī-devakī uvāca — Śrī Devakī said; rūpam — form or substance; yat tat — because You are the same substance; prāhuḥ — You are sometimes called; avyaktam — not perceivable by the material senses (ataḥ śrī-kṛṣṇa-nāmādi na bhaved grāhyam indriyaiḥ); ādyam — You are the original cause; brahma — You are known as Brahman; jyotiḥ — light; nirguṇam — without material qualities; nirvikāram — without change, the same form of Viṣṇu perpetually; sattā-mātram — the original substance, the cause of everything; nirviśeṣam — You are present everywhere as the Supersoul (within the heart of a human being and within the heart of an animal, the same substance is present); nirīham — without material desires; saḥ — that Supreme Person; tvam — Your Lordship; sākṣāt — directly; viṣṇuḥ — Lord Viṣṇu; adhyātma-dīpaḥ — the light for all transcendental knowledge (knowing You, one knows everything: yasmin vijñāte sarvam evaṁ vijñātaṁ bhavati).
Translation: 
Śrī Devakī said: My dear Lord, there are different Vedas, some of which describe You as unperceivable through words and the mind. Yet You are the origin of the entire cosmic manifestation. You are Brahman, the greatest of everything, full of effulgence like the sun. You have no material cause, You are free from change and deviation, and You have no material desires. Thus the Vedas say that You are the substance. Therefore, my Lord, You are directly the origin of all Vedic statements, and by understanding You, one gradually understands everything. You are different from the light of Brahman and Paramātmā, yet You are not different from them. Everything emanates from You. Indeed, You are the cause of all causes, Lord Viṣṇu, the light of all transcendental knowledge.
Purport: 

Viṣṇu is the origin of everything, and there is no difference between Lord Viṣṇu and Lord Kṛṣṇa because both of Them are viṣṇu-tattva. From the Ṛg Veda we understand, oṁ tad viṣṇoḥ paramaṁ padam: the original substance is the all-pervading Lord Viṣṇu, who is also Paramātmā and the effulgent Brahman. The living entities are also part and parcel of Viṣṇu, who has various energies (parāsya śaktir vividhaiva śrūyate svābhāvikī jñāna-bala-kriyā ca). Viṣṇu, or Kṛṣṇa, is therefore everything. Lord Kṛṣṇa says in the Bhagavad-gītā (10.8), ahaṁ sarvasya prabhavo mattaḥ sarvaṁ pravartate: “I am the source of all spiritual and material worlds. Everything emanates from Me.” Kṛṣṇa, therefore, is the original cause of everything (sarva-kāraṇa-kāraṇam). When Viṣṇu expands in His all-pervading aspect, we should understand Him to be the nirākāra-nirviśeṣa-brahmajyoti.

Although everything emanates from Kṛṣṇa, He is ultimately a person. Aham ādir hi devānām: He is the origin of Brahmā, Viṣṇu and Maheśvara, and from them many other demigods are manifested. Kṛṣṇa therefore says in Bhagavad-gītā (14.27), brahmaṇo hi pratiṣṭhāham; “Brahman rests upon Me.” The Lord also says:

ye ’py anya-devatā-bhaktā
 yajante śraddhayānvitāḥ
te ’pi mām eva kaunteya
 yajanty avidhi-pūrvakam

“Whatever a man may sacrifice to other gods, O son of Kuntī, is really meant for Me alone, but it is offered without true understanding.” (Bg. 9.23) There are many persons who worship different demigods, considering all of them to be separate gods, which in fact they are not. The fact is that every demigod, and every living entity, is part and parcel of Kṛṣṇa (mamaivāṁśo jīva-loke jīva-bhūtaḥ). The demigods are also in the category of living entities; they are not separate gods. But men whose knowledge is immature and contaminated by the modes of material nature worship various demigods, according to their intelligence. Therefore they are rebuked in Bhagavad-gītā (kāmais tais tair hṛta-jñānāḥ prapadyante ’nya-devatāḥ). Because they are unintelligent and not very advanced and have not properly considered the truth, they take to the worship of various demigods or speculate according to various philosophies, such as the Māyāvāda philosophy.

Kṛṣṇa, Viṣṇu, is the actual origin of everything. As stated in the Vedas, yasya bhāṣā sarvam idaṁ vibhāti. The Absolute Truth is described later in the Śrīmad-Bhāgavatam (10.28.15) as satyaṁ jñānam anantam yad brahma-jyotiḥ sanātanam. The brahmajyoti is sanātana, eternal, yet it is dependent on Kṛṣṇa (brahmaṇo hi pratiṣṭhāham). The Brahma-saṁhitā states that the Lord is all-pervading. Aṇḍāntara-stha-paramāṇu-cayāntara-stham: He is within this universe, and He is within the atom as Paramātmā. Yasya prabhā prabhavato jagad-aṇḍa-koṭi-koṭiṣv aśeṣa-vasudhādi-vibhu-ti-bhinnam: Brahman is also not independent of Him. Therefore whatever a philosopher may describe is ultimately Kṛṣṇa, or Lord Viṣṇu (sarvaṁ khalv idaṁ brahma, paraṁ brahma paraṁ dhāma pavitraṁ paramaṁ bhavān). According to different phases of understanding, Lord Viṣṇu is differently described, but in fact He is the origin of everything.

Because Devakī was an unalloyed devotee, she could understand that the same Lord Viṣṇu had appeared as her son. Therefore, after the prayers of Vasudeva, Devakī offered her prayers. She was very frightened because of her brother’s atrocities. Devakī said, “My dear Lord, Your eternal forms, like Nārāyaṇa, Lord Rāma, Śeṣa, Varāha, Nṛsiṁha, Vāmana, Baladeva, and millions of similar incarnations emanating from Viṣṇu, are described in the Vedic literature as original. You are original because all Your forms as incarnations are outside of this material creation. Your form was existing before this cosmic manifestation was created. Your forms are eternal and all-pervading. They are self-effulgent, changeless and uncontaminated by the material qualities. Such eternal forms are ever-cognizant and full of bliss; they are situated in transcendental goodness and are always engaged in different pastimes. You are not limited to a particular form only; all such transcendental, eternal forms are self-sufficient. I can understand that You are the Supreme Lord Viṣṇu.” We may conclude, therefore, that Lord Viṣṇu is everything, although He is also different from everything. This is the acintya-bhedābheda-tattva philosophy.