金剛般若波羅蜜經註解 1.21

1.21

已上如是等六事冠於諸經之首謂之通序，如來臨滅度時，阿難問佛：「一切經前當安何語？」佛言：「當安『如是我聞』等語，非但我法如是，三世諸佛法皆如是。」

These six matters above precede all sūtras and are called the general preface. When the Tathāgata was approaching parinirvāṇa, Ānanda asked the Buddha: 'What words should be placed at the head of all sūtras?' The Buddha said: 'You should place words such as "Thus have I heard". Not only is my Dharma thus, but the Dharma of all buddhas of the three periods of time is thus.'