Yahya related to me from Malik that he had heard that Abd ar-Rahman ibn Abi Bakr was visiting A'isha, the wife of the Prophet, mayAIIah bless him and grant him peace, on the day that Sad ibn AbiWaqqas died, and he asked for some water to do wudu. A'isha said tohim, ''Abd ar-Rahman! Perform your wudu fully, for I heard theMessenger of Allah, may Allah bless him and grant him peace, say, 'Woeto the heels in the fire.' "
USC-MSA web (English) reference: Book 2, Hadith 5
Arabic reference: Book 2, Hadith 36