法華義疏 5.280

5.280

「而作是念」下，第二、自序長者己之已出。所以自序之己出者，意在子之未免也。「所燒之門」者，明所出處也。此詺三界限域為門，故後文云「今此三車皆在門外」，即其證也。

From 'and had this thought' downward is the second part, recounting that the elder himself had already escaped. The reason he recounts his own escape is that his concern lies in the children's failure to avoid [the fire]. 'The burned gate' explains the place of escape. This designates the boundary of the three realms as the gate; hence the later text says, 'Now these three carriages are all outside the gate,' which is its proof.