藥師經疏 1.104

1.104

經。第四橫者為火所燒　四火來焚燒此人不定壽業。是焚燒眾生增上果。若遇順緣資助。則不為火焚。壽命延長。如其不爾則為火燒壽命短促故為橫死。

Sūtra: "The fourth untimely death is being burned by fire."
Four: fire burning. This person's karma for lifespan is indefinite; it is the dominant result of burning sentient beings. If they encounter supportive conditions to aid them, they will not be burned by fire, and their lifespan will be prolonged. If not, they will be burned by fire and their lifespan will be short; therefore it is an untimely death.