大般涅槃經義記 5.271

5.271

就知足中，先問起發，次辯，後結。辯中，初言「謂飲食」等外中知足，行、住、坐等內中知足，「行住坐臥」身業知足，「睡之與寤」意業知足，「語之與默」口業知足。

Within "knowing contentment," it first questions to initiate [the topic], next analyzes it, and finally concludes. In the analysis, the initial statement "namely, food and drink" and so forth is contentment regarding the external; walking, standing, sitting, and so forth are contentment regarding the internal; "walking, standing, sitting, and lying down" is contentment in bodily karma; "sleeping and waking" is contentment in mental karma; "speaking and remaining silent" is contentment in vocal karma.