(Nágárjuna, Múlamadhyamakáriká 15:10)To say "it is" is to grasp for permanence. To say "it is not" is to adopt the view of nihilism.
Therefore a wise person does not say "exists" or "does not exist".
(Ibid. 18:6-12)Although the term "self" is caused to be known of, and although "no self" is taught, no "self" nor any "nonself" whatsoever has been taught by the Buddha's.
The designable is ceased when & where the range of thought is ceased, for Nirváṇa is Dharmatá [i.e. the suchness of dharma], unarisen and unstopping.
Everything is actual, or not actual, or actual and not actual, or neither actual nor not actual: this is the Buddhas' teaching.
Independent, peaceful, not delusionally diversified by delusional diversification, devoid of mental construction, without variation, this is the mark of thatness.
Whatsoever originates dependantly, is not insofar, that and only that.
Nor is it the other; therefore, it is neither exterminated nor eternal.
Not singular, not plural, not exterminated, not eternal.
This is the immortal teaching of the Buddha's, lords of the world.
And again, when the disciples are destroyed, when complete Buddha's do not arrive, [in such a case] the jñána [i.e. gnosis] of the independently enlightened Buddha's proceeds without association with teachings.
It doesn't seem especially contrary to Theravāda Buddhism, but there are certain features that mark it as not coming from that specific tradition.
Also, anyone or everyone is free to think Nāgārjuna is full of nonsense, just please do it respectfully.