It was narrated from Abu Hurairah that:
The Prophet said: "Perform ablution after (eating) that which has been changed by fir." Ibn 'Abbas said: "Should I do ablution after (touching) hot water?" Abu Hurairah said: "O son of my brother, when I narrate a Hadith of the Messenger of Allah to you, then do not try to make examples for it."
English reference: Vol. 1, Book 1, Hadith 485
Arabic reference: Book 1, Hadith 523