In silent recitation, what are the mind that recites and the mind that knows the recitation?

Whether reciting a mantra aloud or silently, it is the solitary consciousness (mano-vijñāna-eka-citta) that recites; the recitation of the manas is without language and words. The knowing that knows the silent recitation is the power of introspection (pratyavekṣā-bala) of the mind consciousness; the mind consciousness's power of introspection is precisely the self-validating cognition (svasaṃvedana), whereby the solitary consciousness discerns and introspects upon the solitary consciousness itself. Of course, if the recitation has become very proficient, there is also the recitation and knowing of the manas. When the mind consciousness silently recites, the manas knows; when the mind consciousness introspects, the manas also knows—this knowing is deeply hidden, hard to see and hard to observe. The manas takes the solitary consciousness's introspective function and its function of silently reciting the mantra as its own functions, believing that it is itself who recites and who knows. 

If one's meditative concentration (samādhi) is fairly good, the manas can also participate in reciting the mantra, and the mind consciousness can observe this, but one cannot clearly distinguish the boundaries between the respective functions of the mind consciousness and the manas, so they are easily confused. When there is meditative concentration, first, body and mind can be separated, clearly and distinctly; their connection is not so close. The sixth and seventh consciousnesses can also each be separated, standing apart at some distance from each other, only then do they appear clearly and distinctly, and each dharma gives a sense of being illusory. Without meditative concentration, the various dharmas are twisted together and inseparable, and cannot be seen clearly, so the mixed-together dharmas feel very real and very actual; the grasping (upādāna) is then strong, leading to heavy afflictions. The benefits of meditative concentration are beyond enumeration; without meditative concentration, do not claim to have spiritual cultivation.