(25) باب مَنْ لَعَنَهُ النَّبِيُّ صلى الله عليه وسلم أَوْ سَبَّهُ أَوْ دَعَا عَلَيْهِ
A'isha reported that two persons visited Allah's Messenger (ﷺ) and both of them talked about a thing, of which I am not aware, but that annoyed him and he invoked curse upon both of them and hurled malediction, and when they went out I said:
Allah's Messenger, the good would reach everyone but it would not reach these two. He said: Why so? I said: Because you have invoked curse and hurled malediction upon both of them. He said: Don't you know that I have made condition with my Lord saying thus: O Allah, I am a human being and that for a Muslim upon whom I invoke curse or hurl malediction make it a source of purity and reward.
Reference: Sahih Muslim 2600 a
In-book reference: Book 45, Hadith 112
USC-MSA web (English) reference(deprecated numbering scheme): Book 32, Hadith 6285