四分律行事鈔資持記 2.392

2.392

檢挍中。所以不得者，恐奪賊物，反成盜故。投竄者，古云：空其一室，夜暗，令眾人過，投物於中；竄，即放也。誦呪者，世有呪術能獲盜者。卜筮擲筊，義同不合。

In investigating: the reason why one must not do so is the fear that forcibly taking the thief's property would in turn constitute theft. As for 'casting in secret' (toucuan), the ancients said: empty a room, and in the dark of night have everyone pass through and throw the object inside; 'cuan' means to let go. 'Chanting spells' refers to spells in the world capable of catching thieves. Divination by stalks and casting divination blocks are doctrinally the same as not being permissible.