What four? It’s when a mendicant meditates by observing an aspect of the body—keen, aware, and mindful, rid of covetousness and displeasure for the world. They meditate observing an aspect of feelings … mind … principles—keen, aware, and mindful, rid of covetousness and displeasure for the world. It’s because of not developing and cultivating these four kinds of mindfulness meditation that the true teaching doesn’t last long after the final quenching of the Realized One. It’s because of developing and cultivating these four kinds of mindfulness meditation that the true teaching does last long after the final quenching of the Realized One.”

Linked Discourses 47.23 3. Ethics and Duration Decline

At one time the venerables Ānanda and Bhadda were staying near Pāṭaliputta, in the Chicken Monastery. Then in the late afternoon, Venerable Bhadda came out of retreat, went to Venerable Ānanda, and exchanged greetings with him. When the greetings and polite conversation were over, he sat down to one side and said to Ānanda: “What’s the cause, Reverend Ānanda, what’s the reason why the true teaching declines? And what’s the cause, what’s the reason why the true teaching doesn’t decline?”