Al-ʿAbbās al-Qurashī—one of Tāhir’s foremost disciples (1)—said: “I exerted myself to observe Tāhir’s ʿaqd (string-hand lock), but could not, until I went with him to the bathhouse. There he brought his kustubān (thumb-ring) out of his clothes; I examined it and found no mark upon it whatsoever. I then understood that the whole secret (2) and soundness of archery lies in the thumb-ring.”

Al-Ṭabarī said: “ʿAbd al-Raḥmān told me (3): ‘Penetration (nakāyah) rests on ten factors: nine belong to perfect, faultless wafāʾ, and one to the archer himself.

“Wafāʾ is of two kinds. The first (4) is for the arrow-head to reach the first joint of the thumb. Those who adopt this limit condemn anyone who lets the head pass beyond that joint, arguing: ‘The head is an enemy, and no one should allow an enemy to enter against himself.’

“The second kind is for the arrow-head to reach the space between the two thumb joints.

“ʿAbd al-Raḥmān said: ‘We heard from our shaykhs that drawing so that the arrow-head projects beyond the shaft will drive a full shibr—one span—through a shield, and that they likened the first wafāʾ to the smoke that reaches the enemy from the kindled fire they shoot, while the second is like the very fire striking them.

“Some have said that wafāʾ extends only to the tip (5) of the nail, but others have deemed that view weak.’”