Abu Dawud
Purification (Kitab Al-Taharah)
Book Number: 001 / Hadith Number: 195
Narated By Umm Habibah : Abu Sufyan ibn Sa'id ibn al-Mughirah reported that he entered upon Umm Habibah who presented him a glass of sawiq (a drink prepared with flour and water) to drink. He called for water and rinsed his mouth. She said: O my cousin, don't you perform ablution? The Prophet (pbuh) said: Perform ablution after eating anything cooked with fire, or he said: anything touched by fire.
Abu Dawud said: The version of al-Zuhri has: O my paternal cousin