Musnad Ahmad 27:332

Waki’ narrated to us, Abdullah ibn Nafi’ narrated to us, from his father, from Ibn Umar, who said: The Messenger of Allah (peace and blessings of Allah be upon him) said: "Let none of you hasten from his food for the prayer." He said: And Ibn Umar would hear the iqamah while he was eating dinner, yet he would not hasten.