aham brahmasmi comes from the Brhadaranyka Upanishad verse 1.4.10.
The full verse (translated by Gambhirananda) -
This was indeed Brahman in the beginning. It know only itself as "I am Brahman" (aham brahmasmi).
Thankyou for this wonderful insight sir.
This "I am Brahman" is the first thought in creation, which is called Divine Thought or God thought or "Conscious of I AM".
This "I am Brahman" is the first thought thought and simultaneously Saguna Brahman came into existence. Whomever Contemplate on "I am Brahman"
become Saguna Brahman, full blissful, full consciousness, full Love, full Universe, full 5 sheaths, but cannot realise the Self or Nirguna- Brahman by any contemplation or method or Shravana-Manana-Nidhidhyasana or Eightfold paths or Devotion or etc..
Nirguna Brahman is Me, Advaita, when one goes into silence beyond experience beyond methods beyond paths beyond knowledge beyond consciousness beyond thoughts.
Any path/method/contemplation/etc. make one reach only Ishwara or Saguna Brahman or God with 3gunas balanced or Ardhanarishvar, but not the Whole Brahman/Self, as it is beyond consciousness and experiences/thoughts/knowledge are all bound to Consciousness, combination of Purusha and Prakriti. "I am Brahman" is just a thought evolved from Consciousness because of joining of Purusha and Prakriti. "I am Brahman" is bound to Prakriti. Saguna Brahman is bound to Prakriti. Prakriti is a manifestation and never idle, whereas Purusha is idle always. The subject-Purusha-Experiencer can only experience the Prakriti (Ahankar-Intellect-Mind-Prana-Body-Universe) but not itself.
"I am Brahman" is the Ahankar in Antahkarana. Ahankar is the Individualization, and after that first "I am Brahman", the Individualization created a Pure Bliss through Consciousness/Antahkarana/Pond appeared, and from that Bliss Hiranyagarbha came and creation of "Vedas-Intellect-Mind-Prana-Universe" everything came about. From the Bliss in Consciousness appeared - to the small atoms/Sub-Atmoic Particles/Planck's length/Waves, everything is Thought - Advaitins call it as Illusion/Unreal. I first calling it as Unreal, but it doesn't makes sense because of many questions/views raised in another forum, so it is just Thought/Waves, which cannot be said as Real also not as Unreal, that is Maya.
IMHO, in my Profile Pic, the bubbles are the Consciousness and the first thought/Word came inside the Bubble is "I" or "I AM" or "I AM BRAHMAN" and one can still reach that thought in the cave of right heart, the space from where it arises and links everyone/everything in this world and the other, the Ashwattha tree said in Bhagavat Gita, and reach the Bliss in the way one thinks about it. Ifone thinks about it as Aroopa-like Shankara and Buddha, One reaches there (Brahma Loka) and experience the Bliss and attain Moksha one day and remain there Blissfully until the Maha Pralaya. If one thinks about it as in a form and as a devotee to that form or himself as that form, then one reaches there and experience the Bliss, the 10 to the power 20 times of happiness experienced by a man with money and fame here and attain Moksha one day and never return back to other four sheats and experience only the Bliss, in the form one thought/believe about, until the death of Hiranyagarbha.
But, No one knows/perceives the Self/Brahman without Prakriti, even Ishwara can't. Even God cannot perceive the Nirguna Brahman and only remains
silence to all the questions asked about the Nirguna Brahman, where no word/thought/experience/knowledge/ignorance/existence/non-existence/anything penetrate as it is beyond Consciousness/Bubbles/Antahkarana/Pond.
Even in Brihadaranyaka Upanishad, it's clearly said that "Knower cannot be known, cannot be perceived, adrstam, etc.. One Can only reach the Consciousness as an experience, which is fully Blissful, but beyond it one cannot go/think/know/perceive/talk about."