大毘盧遮那成佛經疏 13.206

13.206

次除業佛頂，如前鉤印即是也。謂作向內相叉合掌，而屈右手風指令如鉤形，二空亦右絞壓左。今單手，即右手為拳，竪風指稍屈上節。

Next is Vikiraṇoṣṇīṣa, which is just like the previously described hook mudrā. That is, form an inward-interlocking añjali, bend the right wind finger into the shape of a hook, and cross the two space fingers with the right pressing the left. Now, with a single hand: form a fist with the right hand and erect the wind finger, slightly bending the upper joint.