大般涅槃經疏 1.22

1.22

Furthermore, as for the five prefaces prefacing the four virtues: 'Thus' generally prefaces the four virtues; 'I have heard' prefaces bliss; 'at one time' prefaces purity; 'dwelling place' prefaces permanence; and 'hearing together' prefaces the self (and so on). By this example, the five prefaces preface the essential meanings of the sūtra, all conforming to this without further extensive explanation; consider other examples accordingly.