Anas ibn Mālik (may Allah be pleased with him) reported that the Messenger of Allah (may Allah's peace and blessings be upon him) said: "If the supper is served, then start eating it before praying the Maghrib prayer, and do not be hasty in finishing it."
If the food is served at the same time that the prayer is about to be performed, then start eating the food before you pray, even if the time for the prayer is a short time, such as that of the Maghrib prayer. The reason is to keep the mind focused on the prayer during the prayer, and not be preoccupied by the food. Abu Ad-Dardā said: "From the signs of a sound mind is to finalize your needs so that the mind is free to focus during the prayer. Al-Bukhāri narrated this Hadīth in a suspended narration.