佛頂尊勝陀羅尼經教跡義記 2.65

2.65

唐云金剛鉤鎖身清淨也。解曰：凡夫不防，多有漏失，縱有少慎不出二乘，豈同殊勝祕密真言？若受得金剛鉤鎖契印而有妄失，豈不堅固耶？故身清淨猶若金剛，鉤鎖永牢而無有失。又解：欲令有情具無礙智，於空不滯、於有體虛，以五智相屈曲如鉤，能鉤眾生出牢有海，能鉤聖智入眾生心。若有菩薩作佛事時，布身鉤鎖，及持此鉤印，鉤於十方界諸佛菩薩，如風疾至，加持此身即成鉤鎖也。

In Chinese it means: "The body pure as a vajra chain-hook." The explanation states: Ordinary beings do not guard [themselves] and have many outflows and lapses; even if they exercise a little caution, they do not transcend the two vehicles; how could they match the extraordinary esoteric mantra? If, after receiving the vajra chain-hook mudrā, one were to suffer negligent lapses, how could it be firm? Therefore, the body is pure just like vajra, and the chain-hook is eternally firm and without any lapse. Another explanation: Desiring to cause sentient beings to possess unhindered wisdom—unobstructed by emptiness and with their essence void regarding existence—the forms of the five cognitions curve like hooks, able to hook sentient beings out of the firm ocean of existence and able to hook the noble wisdom into the minds of sentient beings. When a bodhisattva performs Buddha-work, arranging the chain-hook upon the body and holding this hook mudrā, it hooks the Buddhas and bodhisattvas of the realms of the ten directions, who arrive swiftly like the wind; empowering this body, it becomes the chain-hook.