"At Savatthi. Seated to one side, that mendicant said to the Buddha: “Sir, is there any form at all that’s permanent, everlasting, eternal, imperishable, and will last forever and ever? Is there any feeling … perception … choices … consciousness at all that’s permanent, everlasting, eternal, imperishable, and will last forever and ever?” “Mendicant, there is no form at all that’s permanent, everlasting, eternal, imperishable, and will last forever and ever. There’s no feeling … perception … choices … consciousness at all that’s permanent, everlasting, eternal, imperishable, and will last forever and ever.”
Then the Buddha, picking up a little bit of dirt under his fingernail, addressed that mendicant: “There’s not even this much of any form that’s permanent, everlasting, eternal, imperishable, and will last forever and ever. If there were, this living of the spiritual life for the complete ending of suffering would not be found. But since there isn’t, this living of the spiritual life for the complete ending of suffering is found.
There’s not even this much of any feeling …
perception … choices …
consciousness that’s permanent, everlasting, eternal, imperishable, and will last forever and ever. If there were, this living of the spiritual life for the complete ending of suffering would not be found. But since there isn’t, this living of the spiritual life for the complete ending of suffering is found.
What do you think, mendicant? Is form permanent or impermanent?” “Impermanent, sir.” “Is feeling … perception … choices … consciousness permanent or impermanent?” “Impermanent, sir.” … “So you should truly see … Seeing this … They understand: ‘… there is no return to any state of existence.’”
So from this and hundreds of similar quotes it's quite clear that nibbana is not consciousness as nibbana is permanent, and all consciousness is said to be temporary. A common argument against this is that nibbana supposedly is consciousness and is hinted at in other suttas and that the Buddha meant more than is stated in the above sutta, or that he was deliberately omitting listing some other type of consciousness every single time he discussed the aggregates or the temporary nature of all consciousness. The natural problem with that is that the Buddha said what he meant. If he said "All consciousness" then that's what he meant. This is apparent when we consider the following quotes:
"I have taught Dhamma, Ananda, making no 'inner' and 'outer': the Tathaagata has no 'teacher's fist' in respect of the doctrines."
No hidden teaching, he taught everything up front.
The acceptance of this dichotomy between conventional and transcendental language is widespread today, as is the suppositious parallel distinction between conventional and absolute truth, or reality. Therefore some may be surprised to learn that such a distinction (whether with regard to language, truth, or reality) ... is of later invention and is not to be met with in the Suttas. Quite the contrary, it is specifically and repeatedly condemned. At M. 99: ii,202, for instance, the Buddha goes out of his way to lead his listener to acknowledge the superiority of conventional speech (as well as of speech that is well-advised, spoken after reflection, and connected with the goal) over unconventional speech (and also over speech that is ill-advised, etc.). And consistent with this, at M. 139: iii,230 the monks are advised that when teaching they should (among other things) “not deviate from recognized parlance.
The suttas, then, clearly assert that they are to be understood as saying what they mean. They are not to be interpreted, for to do so must result in misunderstanding them.
The common argument from here is something like: well nibbana is said to be consciousness in some suttas, and that nibbana consciousness is outside the all, so the Buddha omitted it every time he spoke about the aggregates.
To reply to that we have:
nowhere in the Nikayas is Nibbana described as consciousness
-Bhikkhu Bodhi, note to MN 49
and when people use "Consciousness non-manifest, infinite, radiant all around" from DN 11 amd MN 49 to prove that nibbana is consciousness they are missing two things:
One: in MN 49 it is probably a typo,
the Sri Lankan, Thai, and English editions of the Pali attribute the phrase to Brahma, not the Buddha, while only the Burmese attributes it to the Buddha. (The commentary attributes it to the Buddha and says it refers to Nibbana; Burmese texts are notorious for incorporating ‘corrected’ readings from the commentary.)
-Bhikkhu Sujato, "Nibbana is still not Vinnana"
Two: for DN 11
It is in the next lines of the verse, which are usually overlooked by the viññāṇa = Nibbana school, that the Buddha’s true position is stated. With the cessation of viññāṇa all this comes to an end. The ‘infinite consciousness’ is merely the temporary escape from the oppression of materiality, but true liberation is the ending of all consciousness.
-Bhikkhu Sujato "Vinnana is not Nibbana, really it just isn't"
Sujato also makes this excellent point:
When passages such as the ‘anidassana vinnana’ or the ‘pabhassara citta’ are invoked to lend support for the notion that Nibbana is an eternal cosmic awareness that survives the death of an arahant, the first question we should ask is, ‘Do these phrases actually refer clearly to the state of an arahant after death?’ If they don’t, they are irrelevant to the problem. We all agree that an arahant is conscious before their death.
Arguments for the ‘eternal-consciousness Nibbana’ almost invariably tend to slip from talking about the citta or vinnana in this life to the state after death. It is a subtle sleight of hand, which pivots on the ambiguity of the term Nibbana, and is hidden by the conceptual fog that mere mention of the term evokes.
-Bhikkhu Sujato "Nibbana Remains Not Vinnana"
And of course the usual argument to all of the above is endless twisting and turning about the texts to prove that nibbana is self or consciousness or that there is a special consciousness outside the five aggregates that is self and so on. Taking the above into consideration, particularly that the Buddha said what he meant, we can assume that if nibbana was self or consciousness or if there were some special consciousness outside the aggregates, the Buddha would have stated it clearly and repeatedly as he did with most of his teachings.
Bhikkhu Sujato makes some points in this direction on his comments on his blog post on the matter:
The Buddha was so very very emphatic that the end of dependent origination was the end of all forms of consciousness. Making distinctions between “consciousness” and “awareness” and the like is no use, since these do not apply in the suttas.
Unfortunately, most Buddhist commentators on this point are not familiar with the relevant pre-Buddhist Upanishads; for in those texts, it is precisely vijnana (= Pali vinnana) that is the “Universal Awareness” that survives all. If you read what the Upanishads say about vijnana, side by side with what the Buddha says, it becomes perfectly clear that the Buddha was specifically adopting the Upanishadic terminology in order to refute it.
If what the Buddha taught is really in essence the same as the Upanishads–and the ideas that you good gentlemen are talking about are, indeed, Upanishadic–then why was he so chronically unable to say so clearly? Why did he not repeat, as part of the basic definition of Nibbana, that it meant “an eternally lasting radiant omniscient transcendent consciousness”. It’s not so hard; I can do it, and the Upanishadic teachers could. Why did the Buddha, so extraordinarily clear and analytical in all things that matter, fail to say what he meant? Why, in all the dozens of epithets and descriptions of Nibbana, did he so scrupulously avoid anything that implies an existent state? Why, then, do those who search to validate such ideas in the Suttas constantly bringing up the same few, obscure passages of poetic or dubious interpretation? Passages which, moreover, have been shown time and time again to not mean what they are supposed to. The pabhassara citta in the canon, for example, clearly refers to the mind that is developed through samadhi; and if it can be developed it cannot be unconditioned. If actually you consider the passages that supposedly support the idea of Nibbana as a transcendental consciousness, they invariably undermine any such tendency by phrasing themselves in the negative: “There is the unborn…” It’s an emphatic assertion of a negative, not of a positive.
Nibbana is supposed to be threatening. It’s supposed to be disturbing. That’s why, when the Devas or others of limited ability here of it, they are terrified and traumatized. Who gets traumatized by the idea that they will live forever as a transcendent consciousness? Nibbana poses the ultimate existential question, which is why the Buddha always described in ontologically in the negative. At the same time, however, he described it psychologically in the positive: the peaceful, the shelter, the cool, the ultimate bliss. But we can’t realize that state of peace as long as we still attach to refined forms of suffering such as a transcendent consciousness.
-Bhikkhu Sujato's comment on "Vinnana is not nibbana really it just isn't"
In summary: if nibbana were self or consciousness or if there was an extra consciousness outside the aggregates to facilitate these or other things, the Buddha would have said it, clearly and repeatedly, in many different ways in the thousands of suttas of the nikayas. Since he didn't, and actually ruled these ideas out hundreds of times and only a very few vague, sparse quotes support them, and then only with interpretation and explanation, we've much reason to side with Bhikkhu Sujato, all the other Bhikkhus and Bhikkhunis who agree with him and the entire classical Theravada school.
Never read anything I write as an accurate statement about anything whatsoever. First, look to wiser ones than I. Look to wise texts. Unless you can confirm their accuracy from a reliable source, treat my writings like word games, nothing more.