金剛經纂要刊定記 5.226

5.226

則疑。經意云：前雖校量亦未具說，若具說者人必狐疑。狐者，狡獸也，以多疑故，故云狐疑。《述征記》云：「風勁河氷始合，要須狐行，以此物善聽，聽氷下水無流聲，即過也。」魏經即但云疑惑。

"Then they would doubt": the meaning of the sūtra is that although it made comparisons earlier, it did not speak fully; if it spoke fully, people would certainly have fox-like doubts. The fox is a cunning beast; because it is suspicious, it is called 'fox-like doubt'. The Record of Expounding the Campaigns (Shuzheng ji) says: 'When the wind is fierce and the river ice first congeals, it is necessary to follow the fox's path; because this creature is good at listening, it listens for the absence of flowing water beneath the ice before crossing.' The Wei translation simply says 'doubt and confusion'.