The same setting. Sitting to one side the Venerable Bhadda said to the Venerable Ānanda:
“Friend Ānanda, what is the cause and reason why the true Dhamma does not endure long after a Tathagata has attained final Nibbāna? And what is the cause and reason why the true Dhamma endures long after a Tathagata has attained final Nibbāna?”
“Good, good, friend Bhadda! Your intelligence is excellent, your acumen is excellent, your inquiry is a good one. For you have asked me: ‘Friend Ānanda, what is the cause and reason why the true Dhamma does not endure long after a Tathagata has attained final Nibbāna? And what is the cause and reason why the true Dhamma endures long after a Tathagata has attained final Nibbāna?’”
“Yes, friend.”
“It is, friend, because the four establishments of mindfulness are not developed and cultivated that the true Dhamma does not endure long after a Tathagata has attained final Nibbāna. And it is because the four establishments of mindfulness are developed and cultivated that the true Dhamma endures long after a Tathagata has attained final Nibbāna. What four? Here, friend, a bhikkhu dwells contemplating the body in the body … feelings in feelings … mind in mind … phenomena in phenomena, ardent, clearly comprehending, mindful, having removed covetousness and displeasure in regard to the world.
“It is because these four establishments of mindfulness are not developed and cultivated that the true Dhamma does not endure long after a Tathagata has attained final Nibbāna. And it is because these four establishments of mindfulness are developed and cultivated that the true Dhamma endures long after a Tathagata has attained final Nibbāna.” sn.v.173