The Prophet (ﷺ) said:
من أخافَ أهلَ المدينةِ أخافه اللهُ وعليه لعنةُ اللهِ والملائكةِ والناسِ أجمعينَ لا يُقبلُ منه صرفٌ ولا عدلٌ
Whoever frightens the People of Madinah, Allah will frighten him and incurs the curse of Allah, the angels, and all the people, and none of his compulsory or optional good deeds of worship will be accepted
[Graded Saheeh by al-Albani in Saheeha (6/373) and Shaikh Muqbil in Ilhaad al-Khumayni fi Ard al-Haramain (pg. 123-124)]
Jabir (may Allah be pleased with him) said:
تعس من أخاف رسول الله صلى الله عليه وسلم فقال ابناه أو أحدهما يا أبتاه وكيف أخاف رسول الله صلى الله عليه وسلم وقد مات فقال سمعت رسول الله صلى الله عليه وسلم يقول من أخاف أهل المدينة فقد أخاف ما بين جنبي
“May he be miserable the one who frightens the Messenger of Allah (ﷺ). So his sons said: O my father! How can the Messenger of Allah (ﷺ) be frightened when he (ﷺ) has died. He said: I heard the Messenger of Allah (ﷺ) saying: “Whoever frightens the People of Madinah, then he has frightened what is between my sides”
[Saheeh Targheeb no. 1213]
Imam San’aani rahimahullah said:
“Whoever frightens the People of Madinah” that is: with any fear “Then he has frightened what is between my sides” that is: he has frightened me. This is because what is between the two sides is his (ﷺ) heart and the heart is the place of fear” [Tanweer Sharh Jami’ as-Sagheer (10/56)].
Shaikh Abdul-Muhsin al-‘Abbad (may Allah preserve him) said regarding the etiquette of residing in Madinah:
“Ninth: that he beware of harming its people, for harming the Muslims in every place is haram;however, in the sacred lands it is more severe and great. Bukhari reported in his Saheeh from Sa’d ibn Abi Waqqas (may Allah be pleased with him) that he heard the Prophet (ﷺ) say:
لاَ يَكِيدُ أَهْلَ الْمَدِينَةِ أَحَدٌ إِلاَّ انْمَاعَ كَمَا يَنْمَاعُ الْمِلْحُ فِي الْمَاءِ
None plots against the people of Medina but that he will be dissolved (destroyed) like the salt is dissolved in water.
And it is reported in Muslim in his Saheeh from Abu Hurairah (may Allah be pleased with him) that he (ﷺ) said:
مَنْ أَرَادَ أَهْلَهَا بِسُوءٍ – يُرِيدُ الْمَدِينَةَ – أَذَابَهُ اللَّهُ كَمَا يَذُوبُ الْمِلْحُ فِي الْمَاءِ
He who intends to do harm to its people (he meant Medina), Allah would efface him as salt is dissolved in water”.
Faisal Ibn Abdul Qaadir Ibn Hassan