The Tathagata exists after death’ — this craving-standpoint, this perception-standpoint, this product of conceiving, this product of elaboration, this clinging-standpoint: That’s anguish.
‘The Tathagata doesn’t exist after death’…
‘The Tathagata both does and doesn’t exist after death’…
‘The Tathagata neither does nor doesn’t exist after death’ — this craving-standpoint, this perception-standpoint, this product of conceiving, this product of elaboration, this clinging-standpoint: That’s anguish.

https://www.accesstoinsight.org/tipitaka/an/an07/an07.051.than.html

“If there is the view ‘the world is finite,’ …
‘the world is infinite,’ …
‘the soul is the same as the body,’ …
‘the soul is one thing and the body another,’ …
‘after death a Tathāgata exists,’ …
‘after death a Tathāgata does not exist,’ the holy life cannot be lived …  
If there is the view ‘after death a Tathāgata both exists and does not exist,’ the holy life cannot be lived; and
if there is the view ‘after death a Tathāgata neither exists nor does not exist,’ the holy life cannot be lived.

Whether there is the view ‘after death a Tathāgata both exists and does not exist’ or the view ‘after death a Tathāgata neither exists nor does not exist,’ there is birth, there is ageing, there is death, there are sorrow, lamentation, pain, grief, and despair, the destruction of which I prescribe here and now.

“Therefore, Mālunkyāputta, remember what I have left undeclared as undeclared, and remember what I have declared as declared. And what have I left undeclared?
The world is eternal’—I have left undeclared.
‘The world is not eternal’—I have left undeclared.
‘The world is finite’—I have left undeclared.
‘The world is infinite’—I have left undeclared.
‘The soul is the same as the body’—I have left undeclared.
‘The soul is one thing and the body another’—I have left undeclared.
‘After death a Tathāgata exists’—I have left undeclared.
‘After death a Tathāgata does not exist’—I have left undeclared.
‘After death a Tathāgata both exists and does not exist’—I have left undeclared.
‘After death a Tathāgata neither exists nor does not exist’—I have left undeclared.

“Why have I left that undeclared? Because it is unbeneficial, it does not belong to the fundamentals of the holy life, it does not lead to disenchantment, to dispassion, to cessation, to peace, to direct knowledge, to enlightenment, to Nibbāna. That is why I have left it undeclared

https://www.accesstoinsight.org/tipitaka/mn/mn.063.than.html