四分律比丘含注戒本 1.342

1.342

初制畜長。因阿難得一貴糞掃衣，欲奉迦葉，恐犯故，以迦葉十日當還，因聽畜長齊十日。

(The original regulation on keeping extra robes was: because Ānanda obtained a costly rag-robe and wished to offer it to Kāśyapa, but feared committing an offense, and since Kāśyapa was due to return within ten days, [the Buddha] thereupon permitted keeping an extra robe for up to ten days.)