大乘義章 8.16

8.16

次明四有時分久近。生有死有時分極短，唯止一念。故《雜心》云「生有及死有，是各一剎那。」本有、中有時分不定。本有極短至一念，長則或經億百千劫。中有長短，人說不同。有人宣說：極短一念，極長七日。如此說者，齊七日來必得生處，若七日來不得生處，前陰滅已更受中陰。有人復說：中陰極長壽七七日，七七日來必得生處，若不得處，死而更生。復有人說：壽命不定，乃至父母未和合來，常在不滅。此諸說中，後說為善（此二門竟）。

Next is clarifying the length and duration of the four states of existence. The duration of existence at birth and existence at death is extremely short, lasting only a single thought-moment. Thus the Saṃyuktābhidharmahṛdaya says: "Existence at birth and existence at death are each a single kṣaṇa." The durations of basic existence and intermediate existence are indefinite. Basic existence can be as short as a single thought-moment, or as long as hundreds of thousands of koṭis of kalpas. Regarding the length of intermediate existence, people's explanations differ. Some assert that the minimum is a single thought-moment and the maximum is seven days. According to this view, within the span of seven days one will certainly attain a place of rebirth; if within seven days one fails to attain a place of rebirth, the preceding skandhas cease and one receives intermediate existence anew. Others say that the maximum lifespan of an intermediate existence is seven times seven days (forty-nine days), within which one will certainly attain a place of rebirth; if one fails to attain a place, one dies and is born again. Still others say that its lifespan is indefinite: as long as the parents have not joined together, it persists without ceasing. Among these explanations, the last is the best. (This completes the second gate.)