And the LORD said unto Moses and Aaron,
This is the ordinance of the passover: There shall no foreigner eat of it:
Read Chapter 12
Athanasius the Apostolic
But the deceitful, and he that is not pure of heart and possesses nothing that is pure (as Proverbs says, “To a deceitful man there is nothing good”) shall assuredly, being a stranger and of a different race from the saints, be accounted unworthy to eat the Passover, for “a foreigner shall not eat of it.” Thus Judas, when he thought he kept the Passover, because he plotted deceit against the Savior, was estranged from the city which is above and from the apostolic company. For the law commanded the Passover to be eaten with due observance. But he, while eating it, was sifted of the devil, who had entered his soul.