What is the authenticity of the hadith: "O Allah, I am but a human being, so any Muslim man whom I have insulted, cursed, or flogged, make it for him a purification (zakat) and a mercy"?

The Prophet Muhammad (peace be upon him) was characterized by forbearance, deliberation, and purity of tongue. Allah described him as such in the Holy Quran, and he was described similarly in previous scriptures. His companions knew him by these qualities throughout his life. He even refused to supplicate against the polytheists, despite their deserving it, emphasizing that he was sent as a mercy, not a curser.

The hadith that mentions him (peace be upon him) supplicating against some believers, such as his saying: "O Allah, for any believer whom I have insulted, make that a means of closeness to You on the Day of Resurrection," is an authentic and mutawatir (recurrently transmitted) hadith narrated by a group of companions. This hadith refutes exaggeration regarding the Prophet (peace be upon him), demonstrating that he was a human being who would get angry just as other humans do, but he was infallible from being confirmed in error. Anything that issued from him in terms of insulting or cursing someone who did not deserve it was assured in its outcome; for Allah promised him that He would make it a purification, a reward, and a means of closeness.

Scholars have interpreted this hadith to mean that supplicating against someone who does not deserve it becomes a mercy, expiation, and purification, because the Prophet (peace be upon him) was commanded to judge by outward appearances. Or, that what occurred from him was in the nature of Arab customs of speech that did not intend actual imprecation, so he asked his Lord to make it a mercy and expiation. And that this occurred rarely and exceptionally from him, and he was neither foul-mouthed nor a curser.