金剛經纂要刊定記 2.171

2.171

四念處者。四即身、受、心、法，念謂念慧，處謂身等，即是念慧所安住處。則念是能住，身等四處為所住。於此四處安住念慧，名四念處住，帶數釋也。

"Four applications of mindfulness": the four are body, sensation, mind, and dharmas. "Mindfulness" means mindful wisdom; "application" (basis) means the body and so forth, which are the places where mindful wisdom dwells. Thus mindfulness is what is capable of dwelling, and the four bases such as the body are what is dwelt in. Dwelling mindful wisdom in these four bases is called dwelling in the four applications of mindfulness, a dvigu compound.