Is it true what was narrated on the authority of Al-Zuhri, from Urwah, that "Ali's fingernails wore down from the sheer amount he used to climb upon the wives of the Messenger of Allah, may Allah bless him and grant him peace"? And did Al-Dhahabi change the words "Ali" to "so-and-so" and "a man" in his two books, "Siyar A'lam al-Nubala'" and "Tadhkirat al-Huffaz," when he related this narration?

The report is false and unauthentic. It was narrated by Ibn Adi with an unauthentic chain of transmission. Ibn Abi Dawud did not mention his chain of transmission back to Al-Zuhri. Furthermore, Ibn Abi Dawud did not mention the report as a validated one, but rather in the manner of a hadith (definition) scholar discussing unusual reports with his companions. Al-Dhahabi attributed it to its source so that the reader could verify it. Al-Dhahabi's handling of the report, his omission of Ali's name (may Allah be pleased with him), and his statement, "This is falsehood and manifest fabrication," indicate his trustworthiness and piety.