Washing the feet when one is wearing the shoes, and it is not sufficient for one to pass a wet hand over the shoes (but one should take off the shoes and wash one's feet)

Sahih al-Bukhari · Book 4 · Hadith 166

حَدَّثَنَا عَبْدُ اللَّهِ بْنُ يُوسُفَ، قَالَ أَخْبَرَنَا مَالِكٌ، عَنْ سَعِيدٍ الْمَقْبُرِيِّ، عَنْ عُبَيْدِ بْنِ جُرَيْجٍ، أَنَّهُ قَالَ لِعَبْدِ اللَّهِ بْنِ عُمَرَ يَا أَبَا عَبْدِ الرَّحْمَنِ، رَأَيْتُكَ تَصْنَعُ أَرْبَعًا لَمْ أَرَ أَحَدًا مِنْ أَصْحَابِكَ يَصْنَعُهَا‏.‏ قَالَ وَمَا هِيَ يَا ابْنَ جُرَيْجٍ قَالَ رَأَيْتُكَ لاَ تَمَسُّ مِنَ الأَرْكَانِ …

Narrated `Ubaid Ibn Juraij: I asked `Abdullah bin `Umar, "O Abu `Abdur-Rahman! I saw you doing four things which I never saw being done by anyone of you companions?" `Abdullah bin `Umar said, "What are those, O Ibn Jura…