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. These four kinds of mindfulness meditation should be developed to give up these three defilements.”

Linked Discourses 47.51–62 6. Abbreviated Texts on the Ganges Twelve Discourses on the Ganges River, Etc.