The earliest documented unambiguous references to ‘Being’ goes back to the early Upanishads. From the Chandogya:
‘In the beginning there was ‘Being’ alone; the One without a second‘.
And in the celebrated lines of the Katha Upanishad:
‘Not by speech, not by mind,
Not by sight is It be apprehended.
How else is It comprehended
Otherwise than as: ‘It is’ ?’
And in sharp contrast, here are the relevant lines from the original verses of the Prajna-Paramitha Sutra:
‘If, for aeons countless as the sands on the Ganges, the leader himself would continue to pronounce the word ‘Being’; still, pure from the very start, no Being could ever result from his speaking. That is the practice of wisdom, the highest perfection.‘
Shūnyam stands behind the entire binary of ‘Being’ and ‘Non-Being’. Behind all Modeled-Reconstruction.
Of the two, the popularity of ‘Being’ leaves ‘Non-Being’ in the dust. And the Scholar-Monks of the Prajna-Paramitha Sutra get special credit for choosing to articulate the latter.
At the level of Tat-āgatha, both are left behind [go see: ‘This Unformulated Principle‘ once again].
There is no inevitable leap from ‘Being’ to ‘The One’, as suggested by the line from the Chandogya Upanishad. It was a consequential one though, having birthed many of the slippery derivations that are later found in Vedanthic commentaries.