B.G 14.03
My womb is the 'Great-Brahma' (mahadbrahma), and in it I place the seed of all creation. O Bhārata, from this union arises the birth of all beings.
Gīta Bhāshya 14.03
The word 'mahadbrahma' is the Prakrti. The phrase 'mama yoniḥ', i.e. my womb, if for the purpose of conception, and does not indicate mother.
The 'Great Brahman' is the Prakrti. It is divided into forms such as Lakshmi, Earth, and Durga. Uma, Sarasvati, and others are manifestations of its parts, as are other beings. This is stated in the Kāṣāyaṇa scripture.
"She, in the form of Lakshmi, Earth, Durga, and Great (Mahat) binds through illusion during the creation of the Universe. Uma, the primordial speech, and other beings are part of her essence, sung in all Vedas."
- stated thus.
The phrase "My womb" ('mama yoniḥ') refers to the purpose of conception, not to the mother, as understood from the context of the sentence. This is also mentioned in the Sāmaveda, Śārkarākṣya tradition:
"The goddess Mahā-māyā, womb of Vishnu, though devoid of all sorrows, manifests herself with Vishnu as if sorrowful to delude others."
- stated thus.
Therefore, the display of Sita's sorrow and others is for pretence only. Same is stated in the Kurma Purana. She is not the same as planet Earth. It is mentioned in Saukarayana's scripture:
"The 'bhūḥ' is different; its shadow is the planet Earth, which is lower. Indeed, she is the foundation of the origin of all beings."
- stated thus.
"The great-grandmother of the worlds willingly accepted servitude (of the Lord) of her own free will."
- stated thus in the 'anabhimlāta' (unfaded hearing) Vedic testimonial.
It is also mentioned in the Matsya Purana that she acts of her own free will. Indeed, the word 'mahadbrahma', i.e. great-brahman refers to Prakrti only -
"The two words 'mahatī' (great), and 'brahmani' (Brahman) refer to both Prakrti and Great-Lord (maheśvara)".
- stated thus, right there.
Gīta Tātparya 14.03
In the context, the word 'yoni' means wife.
The word 'yoni' means wife, or place, or the cause of the cosmic womb."
- stated thus, in 'śabdanirṇay', the decision of words.
Here, the word 'yoni' refers to wife. 'In that, I place the embryo' is the rest of the sentence.