[729] How does one dwell contemplating the mind in the mind (citta)? Here someone contemplates a mind with lust (sarāgaṃ cittaṃ) as impermanent, not as permanent … he relinquishes it, does not grasp it. Contemplating it as impermanent, he abandons the perception of permanence … relinquishing it, he abandons grasping. In these seven ways he contemplates the mind. The mind is the establishment (upaṭṭhāna), not the mindfulness; mindfulness is both the establishment and the mindfulness itself. With that mindfulness and that knowledge (ñāṇa) he contemplates that mind. Therefore it is called "the development of the establishment of mindfulness (satipaṭṭhāna) that is contemplating the mind in the mind."
Development (bhāvanā): there are four kinds of development … development in the sense of repeated cultivation (āsevana) … Here someone contemplates a mind without lust, a mind with hatred, a mind without hatred, a mind with delusion, a mind without delusion, a contracted mind, a distracted mind, an exalted mind, an unexalted mind, a surpassable mind, an unsurpassable mind, a concentrated mind, an unconcentrated mind, a liberated mind, an unliberated mind, eye-consciousness, ear-consciousness, nose-consciousness, tongue-consciousness, body-consciousness, and mind-consciousness, as impermanent, not as permanent … he relinquishes it, does not grasp it. Contemplating it as impermanent, he abandons the perception of permanence … relinquishing it, he abandons grasping. In these seven ways he contemplates the mind. The mind is the establishment, not the mindfulness; mindfulness is both the establishment and the mindfulness itself. With that mindfulness and that knowledge he contemplates that mind. Therefore it is called "the development of the establishment of mindfulness that is contemplating the mind in the mind."
Development: there are four kinds of development … development in the sense of repeated cultivation … Thus one dwells contemplating the mind in the mind.
English translation from the Pali (Siam Raṭṭha edition) — under review, not for citation.