Anne-Marie Schimmel writes in Mystical dimensions of Islam
Sufism comes close to it [Shankara Advaita Philosophy] in some of the forms developed by the Ibn-Arabi school. Here the Numen is concieved as the Being beyond all Being, or even as the Not-Being, because it cannot be described by any of the categories of finite thought; it is infinite, timeless, spaceless, the Absolute Existence, and the only reality.
In Hegels theory, Being is announced to be an indeterminate substance, and its negation, Not-Being, is Nothing. (he goes on to show that they are in some sense identical - but this irrelevant to the discussion here).
To take Not-Being as being identical with Nothing one supposes that all that is - is Being; and thus what is not - ie has no existence, is nothing. This might be termed an ontological argument, as we've not injected the limits of human thought here; and typically in the Early Modern period, one says God Exists, ie by Spinoza, and one takes the only (Real) Being as God; and so its negation, Not-Being is Nothing.
But explicitly putting in the limits of thought, or in Schimmels phrasing finite thought, one calls what is within this limit as Being; recall here that Wittgenstein called language is the limit of thought; Are we then entitled to say that Non-Being is Nothing? Can there be 'something' which can't be Being - so the word 'something' is being used advisedly here? One might call this an epistemological argument.