Rulings on Wiping over Leather Socks (Mash ‘ala al-Khuffayn)
Question
A man performed wudu and put on leather socks (khuffayn). After he had put on the khuffayn, his wudu was broken, say, before ‘Isha’; he did not remember whether the wudu was broken at eight o’clock or at 7½ o’clock. Now his period [of wiping] ends on the following day at that same time. On the following day he performed wudu for ‘Isha’ and wiped over the khuffayn; and [the previous day] the wudu had been broken before the ‘Isha’ prayer.
Answer
Upon the completion of the full 24 hours the period of wiping ended; it is necessary to take off the khuffayn and wash the feet. If at that time he is without wudu, then, having performed wudu and put on the khuffayn, the period will be reckoned anew. Therefore repeating that prayer is obligatory.
Source: Fatawa Mahmudiyya
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