Mishkat al-Masabih
Book 30, Hadith 39
Arabic hadith text
عَنِ ابْنِ عُمَرَ قَالَ: قَالَ رَسُولُ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسلم:" إِذا رَأَيْتُمْ الَّذِينَ يَسُبُّونَ أَصْحَابِي فَقُولُوا: لَعْنَةُ اللَّهِ عَلَى شركم ". رَوَاهُ التِّرْمِذِيّ
Translation
Ibn `Umar reported God's messenger as saying, "When you see people who revile my companions say, 'God's curse be on your worst ones'." Tirmidhi transmitted it.