Wǔbǎi Luóhàn 五百羅漢 (“five hundred arhats”) is a shortened form of 五百大阿羅漢 Wǔbǎi Dà Āluóhàn. See that note for the legendary collective attribution behind the Sarvāstivāda Vibhāṣā literature (KR6l0010, KR6l0011, KR6l0012).