Sahih Muslim | Book 3 | Chapter 22

Narrated by Zaid b Thabit
Zaid b Thabit reported: I heard the Messenger of Allah (may peace be upon him) say this: Ablution is obligatory (for one who takes anything) touched by fire.

Narrated by 'Abdullah b. Ibrahim b. Qariz
'Abdullah b. Ibrahim b. Qariz reported that he found Abu Huraira performing ablution in the mosque, who said: I am performing ablution because of having eaten pieces of cheese, for I heard the Messenger of Allah (may peace be upon him) say: Perform ablution (after eating anything) touched by fire.

Narrated by 'Urwa
'Urwa reported on the authority of 'Aisha, the wife of the Messenger of Allah (may peace be upon him), saying this: The Messenger of Allah (may peace be upon him) said: Perform ablution (after eating) anything touched by fire.