Musnad Ahmad 1273:12

'Abd al-Samad narrated to us, he said: Harb narrated to us, he said: Yahya ibn Abi Kathir narrated to us, from Abu Salamah, that Abu Sufyan ibn al-Mughirah al-Thaqafi narrated to him, that he entered upon Umm Habibah, the wife of the Prophet, may Allah bless him and grant him peace, and she called for *sawiq* (roasted barley flour) for him, so he drank. Then she said to him: "O son of my brother, will you not perform ablution?" He said: "I have not broken my ablution." She said: "Indeed, the Messenger of Allah, may Allah bless him and grant him peace, said: 'Perform ablution from what fire has touched.'"