Hadith 1753 - Bab 339 (Abomination of Joining As-Salat (The Prayer) when the Food is ready or when one is in desperate need to answer the call of Nature)
Chapter 18 (The Book of the Prohibited actions)

'Aishah (May Allah be pleased with her) said: I heard the Messenger of Allah (Peace be upon him) saying, "No Salat (prayer) should be performed when the food has been served, nor should it be performed when a person is in need of relieving himself."

[Muslim].

"Âisha (das) rapporte: «J"ai entendu le Messager de Dieu (bsdl) dire: «Nulle prière valable quand le repas est servi et nulle prière en retenant les deux impuretés». (Rapporté par Moslem)