四分律比丘含注戒本 1.586

1.586

佛在毘蘭若，聽受夏衣。六群常乞衣，常受衣。跋難陀異處安居，異處受衣。佛在舍衛安居中，大臣為安居施，佛因開而制戒。

The Buddha was in Vairañjā and permitted receiving vassa robes. The group of six [monks] constantly begged for robes and constantly accepted robes. Upananda spent the vassa in one place and accepted robes in another place. When the Buddha was dwelling for the vassa in Śrāvastī, a minister made an offering for the vassa; the Buddha, having made an exception on that occasion, laid down the precept.