瑜伽論記 16.293

16.293

解云：得不還時永不退失故，立學果滿，悲想有心定中，雖復滿，無始雖得，還復退失不定，不說滿，第五種姓亦有退滿，本種有永失義，故并不立滿。

Explanation: When attaining the non-returner [fruit], one never falls away or loses it, hence fulfillment of the fruit of training is established. Although neither-perception is fulfilled among concentrations with mind, having been attained throughout beginningless time it still falls away and is lost without certainty, so fulfillment is not spoken of. The fifth gotra also has falling away from fulfillment, and the original gotra has the meaning of being permanently lost; therefore, fulfillment is not established for it either.