رِيَاضُ الصَّالِحِينَ
Riyad as-Salihin 1552
The Book of the Prohibited actions
Prohibition of Cursing one Particular Man or Animal
وَعَنْ أَبِي هُرَيْرَةَ رَضِيَ اللَّهُ عَنْهُ أَنَّ رَسُولَ اللَّهِ صَلَّى اللَّه عَلَيْهِ وَسَلَّمَ قَالَ: لاَ يَنْبَغِي لِصِدِّيقٍ أَنْ يَكُونَ لَعَّانًا ((رَوَاهُ مُسْلِم)).
Abu Hurairah (May Allah be pleased with him) said: The Messenger of Allah (ﷺ) said: "It does not befit a Siddiq (righteous Muslim) to frequently curse others." [Muslim]
Riyad as-Salihin, 1552