Leviticus 21

The special rules governing the holiness of the priests are laid out here. Priests must maintain a higher standard of ceremonial purity; they are restricted in who they can marry and how they may mourn the dead. The High Priest must maintain the highest standard, never touching a dead body or marrying a widow or a divorced woman. Furthermore, any priest who has a permanent physical defect or injury cannot officiate at the altar or enter the sanctuary, though he may still eat the holy food.