Satipaṭṭhāna is the establishment of mindfulness taught in the discourse of that name, which the Buddha calls a direct path to the purification of beings. The meditator contemplates the body in the body, feelings in feelings, mind in mind and mental objects in mental objects, ardent, clearly knowing and mindful.
Satipaṭṭhāna
The four foundations of mindfulness: body, feelings, mind and mental states.
Also: Satipatthana, four foundations of mindfulness