佛祖統紀 1.87

1.87

次值拘留孫佛。壽五萬歲。彼佛記我。汝於來世。當得作佛。次值拘那含牟尼佛。壽四萬歲。彼佛記我。汝於來世。當得作佛。次值迦葉佛。壽二萬歲。彼佛記我。汝於來世。當得作佛。號釋迦牟尼（已上四佛。在賢劫中。住二十劫。第九減劫。相繼出世。故此文通指來世）我如是。奉事諸佛。修學佛意。爾乃生兜率天宮。住一生補處位（已上並菩薩本行經○涅槃經。此天欲界最勝故。補處菩薩。皆示生其中。為教化眾生故）我今出世。人壽百歲。少出多減（中阿含經）釋迦人壽一萬歲時合出。為觀眾生無機可度。乃至百歲。見苦逼迫。劫將欲末故出乎世（大論○已上並小機所明本迹文）。

Next, he encountered Krakucchanda Buddha, whose lifespan was fifty thousand years; that Buddha prophesied to me: 'In a future life, you shall attain Buddhahood.' Next, he encountered Kanakamuni Buddha, whose lifespan was forty thousand years; that Buddha prophesied to me: 'In a future life, you shall attain Buddhahood.' Next, he encountered Kāśyapa Buddha, whose lifespan was twenty thousand years; that Buddha prophesied to me: 'In a future life, you shall attain Buddhahood, named Śākyamuni.' (The four Buddhas above appeared successively during the ninth decrement kalpa of the twenty kalpas of the abiding period in the Auspicious Kalpa; therefore, this text generally refers to 'a future life.') Having thus attended upon the Buddhas and cultivated the mind of a Buddha, I was then born into the Tuṣita Palace and resided in the position of being one birth away from Buddhahood. (All the above is from the Bodhisattvacaryā-sūtra. The Nirvāṇa-sūtra says that because this heaven is the supreme among the desire realm, all bodhisattvas one birth away from Buddhahood manifest birth therein in order to instruct and transform sentient beings). Now I have appeared in the world when human life is one hundred years, with slight increases and many decreases (Madhyamāgama). Śākya ought to have appeared when human life was ten thousand years, but seeing that sentient beings had no capacity to be saved, he waited until it was one hundred years, when seeing them oppressed by suffering and the kalpa approaching its end, he appeared in the world (Dazhidulun. All the above are passages clarifying the origin and traces for those of lesser capacity).