Is what is mentioned in some history books, especially "One Thousand and One Nights," about Harun al-Rashid—that he was frivolous, drank alcohol, and danced with courtesans—true?

This is a lie and an injustice; for the aforementioned Caliph was one of the best Caliphs, and during his reign, Allah granted conquests, security, and prosperity unparalleled. Furthermore, he had an excellent conduct, used to sit with scholars, and engaged frequently in worship and night prayers, as stated in his well-known biography. As for the mentioned book, it contains fabricated lies concocted by a person who wished to preoccupy the Ummah and waste its time.