大般涅槃經義記 1.143

1.143

問曰：何不望直就彼所得解常，乃就佛乎？釋云：彼常當來未現，冥冥難彰，故就佛論。佛常為昔權迹所隱，今須拂權以顯其實，故約二時無差以顯。呼言純陀，起發其心。施食有二、果報無差，正解常義。施食有二，文少難解，若具，應言受施食人有二，翻者為欲四字成文，略去初受。此云何知？下就受者以辯二故。果無差者，拂權顯實，隨化以論，前受施時是因非果、後受施時是果非因，因果兩差即是無常。據實二時無非佛果，果報無差，所以是常。

Question: Why not explain eternity directly in terms of what he attains, rather than in terms of the Buddha? Explanation: His eternity is in the future and not yet manifest, obscure and difficult to reveal; therefore it is discussed in terms of the Buddha. The Buddha's eternity was concealed by past provisional traces; now one must brush away the provisional to reveal the real; thus it is revealed in terms of the absence of difference between the two times. Calling him by name, 'Cunda', arouses his mind. 'Giving food is of two kinds, and the retribution has no difference' directly explains the meaning of eternity. 'Giving food is of two kinds' has few words and is difficult to understand; if complete, it should say that the person who receives the gift of food is of two kinds; the translator, wishing to compose four-character phrasing, omitted the initial 'receives'. How is this known? Because below the two are distinguished in terms of the recipient. 'The fruit has no difference' brushes away the provisional to reveal the real; if discussed according to transformation: the earlier time of receiving the offering is the cause and not the fruit; the later time of receiving the offering is the fruit and not the cause; the difference between cause and fruit is impermanence. Based on reality, neither of the two times is anything other than the buddha fruit; the fruit and retribution have no difference, and therefore it is eternal.