請觀音經疏闡義鈔 2.70

2.70

經「鉤牙上出」者，「鉤」或作「狗」，字之誤也。《經律異相》、《賢愚經》、《觀佛三昧海經》並作鉤牙。鉤字從金、從扌並通。〈喪大記〉曰「妻於夫拘之」。《經典釋文》音溝。古經字或從扌，故誤為「狗」字也。

Regarding the sūtra's "hooked fangs protruding upward," "hook" (gou) is sometimes written as "dog" (gou), which is an error of the character. The Jinglü yixiang, Xianyu jing, and Guanfo sanmei hai jing all write "hooked fangs." The character gou is interchangeable whether written with the metal radical or the hand radical. The "Sang Daji" states: "The wife binds (ju) the husband." The Jingdian shiwen glosses its sound as gou. Ancient sūtra characters were sometimes written with the hand radical, hence it was mistakenly written as the character for "dog."