勅修百丈清規 5.52

5.52

十誦律云。佛聽蓄杖。其𥎞用鐵為堅牢故。斯蓋行李之善助也。又毘奈耶云。佛聽蓄主丈。有二因緣。一為老瘦無力。二為病苦嬰身故。

The Daśādhyāya Vinaya says: 'The Buddha permitted the keeping of a walking staff; its tip uses iron for firmness; this is an excellent aid for travel.' Furthermore, the Vinaya says: 'The Buddha permitted the keeping of a walking staff for two reasons: first, for being old, emaciated, and lacking strength; second, for being afflicted with illness and suffering.'