Sahih Muslim 1387
Sahih Muslim · Book 15: The Book of Pilgrimage · 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
Abu Huraira and Sa'd reported Allah's Messenger (way peace be upon him) as saying:
وَحَدَّثَنَا أَبُو بَكْرِ بْنُ أَبِي شَيْبَةَ ، حَدَّثَنَا عُبَيْدُ اللَّهِ بْنُ مُوسَى ، حَدَّثَنَا أُسَامَةُ بْنُ زَيْدٍ ، عَنْ أَبِي عَبْدِ اللَّهِ الْقَرَّاظِ ، قَالَ سَمِعْتُهُ يَقُولُ سَمِعْتُ أَبَا هُرَيْرَةَ ، وَسَعْدًا ، يَقُولاَنِ قَالَ رَسُولُ اللَّهِ صلى الله عليه وسلم " اللَّهُمَّ بَارِكْ لأَهْلِ الْمَدِينَةِ فِي مُدِّهِمْ " . وَسَاقَ الْحَدِيثَ وَفِيهِ " مَنْ أَرَادَ أَهْلَهَا بِسُوءٍ أَذَابَهُ اللَّهُ كَمَا يَذُوبُ الْمِلْحُ فِي الْمَاءِ " .
O Allah, bless the people of Medina in their mudd, the rest of the hadith being the same, and in It (this is also mentioned):" He wo intends to do harm to its people, Allah would efface him just as salt it dissolved in water."