What is the prescribed shape or orientation for the drawn line (khatt)?
Chapter on Imamate and Congregational Prayer
Al-Mughni
Book of Prayer
Primary text
The preferable description for the shape of the drawn line resembles the arc of a crescent moon. Ahmad ibn Hanbal indicated this shape when he made a circular motion with his finger like an arch (qantarah). However, any manner in which the line is drawn suffices, whether drawn lengthwise (tulan) or crosswise (ardhan), because the prophetic narration concerning the line is unrestricted in its description, meaning fulfilling the requirement of drawing a line suffices.
Supporting text
While Ahmad seemed to prefer the crescent-like arc, others, such as Ibn Dawud, indicated the line should be drawn lengthwise (tulan). There were differing narrations regarding whether it should be drawn lengthwise or crosswise, but the consensus is that the generality of the command permits flexibility.