妙法蓮華經玄義 9.164

9.164

住迹用本者，上來住迹顯本者，直是迹中隨機方便顯本地理。今言住迹用本者，即是中間，迹至道樹，數數生滅。他身他事者，皆用本地實因實果，種種本法，為諸眾生而作佛事，故言住迹用本，此就師為解。若約弟子者，即是本時妙應眷屬，住於權迹，垂形九道，而用本法利益眾生。文云：「然我今非實滅度，而便唱言當取滅度。如來以是方便，教化眾生。」此是住迹，而用本時滅度而示滅度也。

Abiding in the traces and employing the original source: previously, "abiding in the traces and revealing the original source" simply referred to using skillful means in accordance with capacities within the traces to reveal the principle of the original ground. Now, speaking of "abiding in the traces and employing the original source," it refers to the interim period, tracing up to the bodhi tree, undergoing frequent births and extinctions. Other bodies and other matters all employ the real cause and real fruit of the original ground, along with various original dharmas, to perform buddha-work for all sentient beings; hence it is called abiding in the traces and employing the original source. This is explained with respect to the master. In terms of disciples, they are the wondrous responsive retinue of the original time, abiding in the provisional traces and manifesting forms in the nine realms, while employing the original dharmas to benefit sentient beings. The text says: "Yet now I am not truly extinguished, but I declare that I shall enter extinction. The Tathāgata uses such skillful means to teach and transform sentient beings." This is abiding in the traces while using the extinction of the original time to display extinction.