法華玄論 9.15

9.15

答：若不詑多寶願，何由得集分身佛明本迹義耶？當知此意顯於茲矣。又多寶實有此願。所以然者，諸佛各有誓願，如身子成佛願於淨土而說三乘。多寶本願因此塔以開本迹，以惑者皆謂居在塔者必是身已滅亡，故寄塔以表法身常住也。

Answer: If one did not make use of Prabhūtaratna's vow, how could one gather the emanation-buddhas to illuminate the meaning of root and traces? One should know that this intention is made manifest here. Moreover, Prabhūtaratna truly had this vow. The reason is that all buddhas have their respective vows, just as Śāriputra, upon becoming a buddha, vowed to expound the three vehicles in a pure land. Prabhūtaratna's original vow used this stūpa to open the root and the traces: because deluded people all claim that one who resides in a stūpa must have a body that has already perished, he made use of the stūpa to signify that the dharmakāya is eternally abiding.