大般涅槃經義記 2.117

2.117

上來合竟，自下第三重顯向前加水之相。凡夫所修人天善行如所加乳，妄說常等名為加水。文中先明所加之乳，舉法喻帖。「如是凡夫實不知」下明其加水，文顯可知。

The application above is complete; below is the third part, which re-clarifies the manner of adding water mentioned earlier. The human and heavenly good deeds cultivated by ordinary beings are like the milk added; falsely speaking of eternity and so forth is called adding water. In the text, it first clarifies the milk that is added, adducing the dharma and simile to correspond. "Such ordinary beings truly do not know..." onwards clarifies their adding water, which is evident and can be known from the text.