The prohibition of wishing ill towards the people of Al-Madinah, and that the one who wishes them ill will be caused to melt by Allah
حَدَّثَنَا قُتَيْبَةُ بْنُ سَعِيدٍ، حَدَّثَنَا حَاتِمٌ، - يَعْنِي ابْنَ إِسْمَاعِيلَ - عَنْ عُمَرَ بْنِ نُبَيْهٍ، أَخْبَرَنِي دِينَارٌ الْقَرَّاظُ، قَالَ سَمِعْتُ سَعْدَ بْنَ أَبِي وَقَّاصٍ، يَقُولُ قَالَ رَسُولُ اللَّهِ صلى الله عليه وسلم " مَنْ أَرَادَ أَهْلَ الْمَدِينَةِ بِسُوءٍ أَذَابَهُ اللَّهُ كَمَا يَذُوبُ الْمِلْحُ فِي الْمَاءِ " .
Sa'd b. Abu Waqqas reported Allah's Messenger (ﷺ) as saying: He who intends to do harm to the people of Medina, Allah would efface him just as water dissolves salt.