I say, and with God's success: Whoever has from his foot, below the ankle, less than three fingers from the smallest fingers of the hand, it is not permissible for him to wipe; because it is a condition for the permissibility of wiping that there remains on each foot from the front of the foot in the sock the amount of three fingers from the smallest fingers of the hand; this is to ensure the required amount from the place of wiping. If this amount is not present, it is not permissible for him to wipe. Refer to: Maraqi al-Falah, p. 131, and God knows best.