“Ānanda, take a mendicant who practices like this:
“Idhānanda, bhikkhu evaṃ paṭipanno hoti:
‘It might not be, and it might not be mine. It will not be, and it will not be mine. I am giving up what exists, what has come to be.’
‘no cassa, no ca me siyā; na bhavissati, na me bhavissati; yadatthi, yaṃ bhūtaṃ—taṃ pajahāmī’ti.
In this way
they gain equanimity.
Evaṃ upekkhaṃ paṭilabhati.
They approve, welcome, and keep clinging to that equanimity.
So taṃ upekkhaṃ abhinandati, abhivadati, ajjhosāya tiṭṭhati.
Their consciousness relies on that and grasps it.
Tassa taṃ upekkhaṃ abhinandato abhivadato ajjhosāya tiṭṭhato tannissitaṃ hoti viññāṇaṃ tadupādānaṃ.
A mendicant with grasping does not become extinguished.”
Saupādāno, ānanda, bhikkhu na parinibbāyatī”ti.
“But sir, what is that mendicant grasping?”
“Kahaṃ pana so, bhante, bhikkhu upādiyamāno upādiyatī”ti?
“
The dimension of neither perception nor non-perception.”
“Nevasaññānāsaññāyatanaṃ, ānandā”ti.
“Sir, it seems
that mendicant is grasping the best thing to grasp!”
“Upādānaseṭṭhaṃ kira so, bhante, bhikkhu upādiyamāno upādiyatī”ti?
“Indeed, Ānanda.
“Upādānaseṭṭhañhi so, ānanda, bhikkhu upādiyamāno upādiyati.
For the best thing to grasp is
Upādānaseṭṭhañhetaṃ, ānanda, yadidaṃ—
the dimension of neither perception nor non-perception.
nevasaññānāsaññāyatanaṃ.
Take a mendicant who practices like this:
Idhānanda, bhikkhu evaṃ paṭipanno hoti:
‘It might not be, and it might not be mine. It will not be, and it will not be mine. I am giving up what exists, what has come to be.’
‘no cassa, no ca me siyā; na bhavissati, na me bhavissati; yadatthi, yaṃ bhūtaṃ—taṃ pajahāmī’ti.
In this way they gain equanimity.
Evaṃ upekkhaṃ paṭilabhati.
They don’t approve, welcome, or keep clinging to that equanimity.
So taṃ upekkhaṃ nābhinandati, nābhivadati, na ajjhosāya tiṭṭhati.
So their consciousness doesn’t rely on that and grasp it.
Tassa taṃ upekkhaṃ anabhinandato anabhivadato anajjhosāya tiṭṭhato na tannissitaṃ hoti viññāṇaṃ na tadupādānaṃ.
A mendicant free of grasping becomes extinguished.”
Anupādāno, ānanda, bhikkhu parinibbāyatī”ti.
https://suttacentral.net/mn106/en/sujato