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." (IT)
English reference (IT): Vol. 1, Book 1, Hadith 485 (IT)
Arabic reference (IT): Book 1, Hadith 523 (IT)