Musnad Ahmad 1153:661

Hassan narrated to us, he said: Shayban narrated to us, from Yahya, from Salim, the freed slave of Daws, that he heard Aisha saying to Abd al-Rahman ibn Abi Bakr: "Perform the ablution thoroughly, for I heard the Messenger of Allah, may Allah bless him and grant him peace, saying: 'Woe to the heels from the Fire.'"