Srimad Bhagavatam Canto 07, Chapter 09, Text 30

SB 7.9.30

ekas tvam eva jagad etam amusya yat tvam
 ady-antayoh prthag avasyasi madhyatas ca
srstva guna-vyatikaram nija-mayayedam
 naneva tair avasitas tad anupravistah
Translation by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada: 
My dear Lord, You alone manifest Yourself as the entire cosmic manifestation, for You existed before the creation, You exist after the annihilation, and You are the maintainer between the beginning and the end. All this is done by Your external energy through actions and reactions of the three modes of material nature. Therefore whatever exists — externally and internally — is You alone.
Purport by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada: 
As stated in the Brahma-samhita (5.35):
eko ’py asau racayitum jagad-anda-kotim
 yac-chaktir asti jagad-anda-caya yad-antah
 govindam adi-purusam tam aham bhajami
“I worship the Personality of Godhead, Govinda, who, by one of His plenary portions, enters the existence of every universe and every atomic particle and thus unlimitedly manifests His infinite energy all over the material creation.” To create this cosmic manifestation, Govinda, the Supreme Personality of Godhead, expands His external energy and thus enters everything in the universe, including the atomic particles. In this way He exists in the entire cosmic manifestation. Therefore the activities of the Supreme Personality of Godhead in maintaining His devotees are transcendental, not material. He exists in everything as the cause and effect, yet He is separate, existing beyond this cosmic manifestation. This is also confirmed in Bhagavad-gita (9.4):
maya tatam idam sarvam
 jagad avyakta-murtina
mat-sthani sarva-bhutani
 na caham tesv avasthitah
The entire cosmic manifestation is but an expansion of the Lord’s energy; everything rests in Him, yet He exists separately, beyond creation, maintenance and annihilation. The varieties of creation are performed by His external energy. Because the energy and energetic are one, everything is one (sarvam khalv idam brahma). Therefore without Krsna, the Parabrahman, nothing can exist. The difference between the material and spiritual worlds is that His external energy is manifested in the material world, whereas His spiritual energy exists in the spiritual world. Both energies, however, belong to the Supreme Lord, and therefore in a higher sense there is no exhibition of material energy because everything is spiritual energy. The energy in which the Lord’s all-pervasiveness is not realized is called material. Otherwise, everything is spiritual. Therefore Prahlada prays, ekas tvam eva jagad etam: “You are everything.”
Srimad Bhagavatam Canto 07, Chapter 09, Text 29
Srimad Bhagavatam Canto 07, Chapter 09, Text 31