Sahih Bukhari Volume 001, Book 011, Hadith Number 642.
Narated By Nafi' : Ibn 'Umar said, "Allah's Apostle said, 'If the supper is served for anyone of you and the Iqama is pronounced, start with the supper and don't be in haste (and carry on eating) till you finish it." If food was served for Ibn 'Umar and Iqama was pronounced, he never came to the prayer till he finished it (i.e. food) in spite of the fact that he heard the recitation (of the Qur'an) by the Imam (in the prayer). Narrated Ibn 'Umar: The Prophet said, "If anyone of you is having his meals, he should not hurry up till he is; satisfied even if the prayer has been started."