The inscriptions on the covering of the Kaaba's door
There follow a few words of advice to those who want to visit the Mosque of the Messenger of Allaah (peace and blessings of Allaah be upon him):
1 O you who come to Madeenah, you are in a place which, after Makkah, is the best and noblest of all places, so respect it as it should be respected; honour its sanctity and holiness and observe the best etiquette therein. Know that Allaah has warned of the severest punishment for those who commit evil therein. It was narrated from Abu Hurayrah (may Allaah be pleased with him) that the Prophet (peace and blessings of Allaah be upon him) said: Madeenah is a Haram (sanctuary), so whoever commits evil therein or gives protection to an evildoer, the curse of Allaah, the angels and all of mankind may be upon him. Allaah will not accept any obligatory or naafil deed from him on the Day of Resurrection. Narrated by al-Bukhaari, 1867; Muslim, 1370.
So whoever commits any evil action or offers protection to any evildoer who seeks his help is exposing himself to a humiliating punishment and the wrath of the Lord of the Worlds.