觀彌勒上生兜率天經贊 2.13

2.13

贊曰：下依問具申。有二：初答生處、後答淨穢。此即初也。從今十二年後者，示受記。已求超生死十二緣，故生兜率天而為補處。

The Commentary says: Below, he sets forth [the answer] in full according to the inquiry. There are two parts: first, answering the place of birth; second, answering concerning purity and impurity. This is the first. 'Twelve years from now' indicates the receiving of the prophecy. Having already sought to transcend the twelve links of birth and death, he is therefore born in Tuṣita Heaven to succeed to Buddhahood in the next birth.