[1661] Bhikkhus, do not think evil, unwholesome thoughts (cittaṃ): 'The world is eternal,' or 'The world is not eternal,' or 'The world is finite,' or 'The world is infinite,' or 'The soul (jīva) and the body are the same,' or 'The soul is one thing, the body another,' or 'The Tathāgata exists after death,' or 'The Tathāgata does not exist after death,' or 'The Tathāgata both exists and does not exist after death,' or 'The Tathāgata neither exists nor does not exist after death.' For what reason? Because, bhikkhus, this thinking is not connected with benefit, does not belong to the fundamentals of the holy life, and does not lead to disenchantment, to dispassion, to cessation (nirodha), to peace, to direct knowledge, to full awakening, to Nibbāna.
But when you think, bhikkhus, you should think: 'This is suffering (dukkha)'; you should think: 'This is the origin (samudaya) of suffering'; you should think: 'This is the cessation of suffering'; you should think: 'This is the way of practice leading to the cessation of suffering.' For what reason? Because, bhikkhus, this thinking is connected with benefit; this belongs to the fundamentals of the holy life; this leads to disenchantment, to dispassion, to cessation, to peace, to direct knowledge, to full awakening, to Nibbāna. Therefore, bhikkhus, exertion should be made [to realize]: 'This is suffering' … exertion should be made: 'This is the way of practice leading to the cessation of suffering.'
English translation from the Pali (Siam Raṭṭha edition) — under review, not for citation.