俱舍論記 14.129

14.129

「由彼未解至乃至廣說」者，經部自釋經文。由彼欲受戒者未解近事律儀受量少多，故請問佛：凡有幾種鄔婆索迦能學學處？佛答：有四鄔婆索迦，謂能學一分等。彼受戒者猶未能了，復問世尊：何名能學一分、少分等。乃至廣說世尊為答。此經意說為受戒者故說四種，非約持犯說一分等。

"Because they did not understand ... up to extensive explanation" is the Sautrāntika's own explanation of the scriptural text. Because those wishing to receive the precepts did not understand the lesser or greater amount in receiving the upāsaka discipline, they asked the Buddha: "In all, how many kinds of upāsakas capable of training in the training rules are there?" The Buddha answered: "There are four kinds of upāsakas, namely those capable of training in one portion, etc." The person receiving the precepts still did not fully understand, and further asked the World-Honoured One: "What is meant by capable of training in one portion, a lesser portion, etc.?" up to the extensive explanation of the World-Honoured One's reply. The meaning of this sūtra is that for the sake of those receiving the precepts, the four kinds were spoken of; it is not spoken of as one portion, etc., in terms of maintaining and violating.