Source: Tafsir al-Ahlam al-Kabir (Ibn Sirin)
Eating with a dead person indicates a long life. If the deceased was righteous, it indicates companionship with the righteous. If he was corrupt, it indicates companionship with the corrupt.
Source: Ta'tir al-Anam fi Ta'bir al-Manam (Al-Nabulsi)
Whoever sees himself eating with a dead person will travel far or live among foreign people.
Source: Al-Isharat fi Ilm al-Ibarat (Ibn Shahin)
Eating with the dead indicates sustenance coming from an unexpected source.