Sahih Muslim Book 4, Hadith Number 1146.

Chapter : When food is brought before man and he is inclined to take it, he should not say prayer before eating it and undesirability of prayer while feeling the call of nature.

Jabir reported: The Messenger of Allah (may peace be upon him) said: He who eats garlic or onion should remain away from us or from our mosque and stay in his house. A kettle was brought to him which had (cooked) vegetables in it, He smelt (offensive) odour in it. On asking he was informed of the vegetables (cooked in it). He said: Take it to such and such Companion. When he saw it, he also disliked eating it. (Upon this), he (the Holy Prophet) said: You may eat it, for I converse with one with whom you do not converse.