四分律行事鈔資持記 2.586

2.586

一屏處不定。（佛在舍衛，迦留陀夷與優婆夷共屏覆坐，說非法語；毘舍佉母見白佛。因制。）

First: The Aniyata of a Concealed Place. (The Buddha was in Śrāvastī; Udāyin sat together with an upāsikā in a concealed and covered place, speaking non-dharmic words; Mother Viśākhā saw them and reported to the Buddha. On this account it was instituted.)