三彌勒經疏 1.173

1.173

經曰「是時佛母」以下，第五佛母眾。問：所將眾皆得無學，云何佛父母唯得初果？答：為久住世流通佛法故，不須證無學果也。

From the sūtra's words 'At that time the Buddha's mother' onward, this is the fifth, the Buddha's mother's assembly. Question: The assembly led by her all attained the stage of no-more-learning (aśaikṣa); why did the Buddha's parents only attain the first fruit? Answer: In order to abide long in the world and propagate the Buddha's Dharma, they did not need to realize the fruit of no-more-learning.