"Oneness" or sunnata is the same as no-thingness or no individual essence or anatta. It is not nothingness. It is not the opposite of all is not mine ie. all is me, mine, myself! "One" simply cannot liberate all "beings" from samsara.
Therefore, wherever the doctrine of the egolessness of all existence is rejected, there the Buddha's word is rejected. But wherever, through penetration of the egolessness of all existence, the ego-vanity has reached ultimate extinction, there the goal of the Buddha's teaching has been realized, namely: freedom from all vanity of I and Mine, and the highest peace of Nibbaana.
by Nyanatiloka Mahathera
"'Void world, void world' is said, Lord. In what way is 'void world' said?" — "It is because of what is void of self or self's property that 'void world' is said, Aananda. And what is void of self or self's property? The eye... forms... eye-consciousness... eye-contact... any feeling, whether pleasant or unpleasant or neither-unpleasant-nor-pleasant, that arises born of eye-contact, is void of self or self's property (and likewise with the other five bases)."
— S. XXXV, 85 vol. iv, 54
https://www.accesstoinsight.org/lib/aut ... golessness
"What is perception of not-self? Here a bhikkhu, gone to the forest, or to the root of a tree, or to a room that is void, considers thus: "Eye is not self, forms are not self, ear... sounds... nose... odors... tongue... flavours... body... tangibles... mind... ideas are not self. That is how he abides contemplating not-self in these six in-oneself-and-external bases."
— A. X. 60/vol. v, 109
‘Even now, Ananda, I am one who is much devoted to abiding in emptiness.’
Have I heard this correctly, grasped [learned] this correctly, attended to this correctly, remembered
“Certainly, Ananda, you have heard it correctly, grasped [learned] it correctly, attended to it correctly,
remembered it correctly. As before, Ananda, so do I now often abide in emptiness.
The Lesser Discourse on Emptiness
And what is right speech? Abstaining from lying, from divisive speech, from abusive speech, & from idle chatter: This is called right speech.