妙法蓮華經文句 1.61

1.61

本迹解者，三藏佛應涅槃，慈悲垂迹生身住世。通佛誓願慈悲，扶餘習度眾生作佛事。別、圓佛皆慈悲薰法性，愍眾生故垂應法界。當知四佛住本佛住，以慈悲故住於忍土王城，威儀住世，是名迹住。

In terms of origin and traces: The Buddha of the Tripiṭaka teaching, responding to nirvāṇa, manifests traces out of compassion and abides in the world with a physical body. The Buddha of the shared teaching, out of compassionate vows, maintains residual habitual tendencies to cross over sentient beings and perform the Buddha's work. The Buddhas of both the distinctive and perfect teachings have their Dharma-nature perfumed by compassion, and out of pity for sentient beings, manifest responses throughout the Dharma realm. One should know that the abidings of the four Buddhas are the abiding of the original Buddha; out of compassion he abides in the royal city of the world of endurance, abiding in the world with dignified deportment—this is termed trace abiding.