The relevant body of transmitted evidence places wiping on the upper surface. Even if the sole seems more likely to collect dirt, that intuitive preference does not replace the narrated method.
Ali is reported to have contrasted what mere opinion might suggest with the Prophet’s practice of wiping the top of the khuff.
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Wiping Over Khuffs: Conditions, Duration, Nullifiers, and Splints
The relevant body of transmitted evidence places wiping on the upper surface. Even if the sole seems more likely to collect dirt, that intuitive preference does not replace the narrated method.
Ali is reported to have contrasted what mere opinion might suggest with the Prophet’s practice of wiping the top of the khuff.