Sahih Muslim Book 3, Hadith Number 725.

Chapter : It is permissible to eat without ablution and there is no abhorrence in it and performing of ablution immediately (after that) is not essential.

Ibn ‘Abbas reported: The Apostle of Allah (may peace be upon him) came out of the privy, and he was presented with some food, and the people reminded him about ablution, but he said: Am I to say prayer that I should perform ablution?