Is there an authentic Hadith concerning the mathnāt? If so, what is that Hadith, both its chain of narration (sanad) and text (matn)?

A hadith is narrated in the "Mathna" by Al-Darimi in his Sunan, in which Amr ibn Qais mentions that he went with his father to Yazid ibn Mu'awiyah to offer condolences and congratulations. He heard a man in the mosque say that among the signs of the Hour are: the elevation of the wicked and the debasement of the good, the prevalence of speech and the concealment of action, and that the Mathna will be recited, and no one will be found to change it. The man was asked about the Mathna, and he said: "Whatever is written down other than the Qur'an." Then he said: "Therefore, adhere to the Qur'an, for by it you are guided, by it you are rewarded, and about it you will be questioned." Amr did not know the man until later, when he was told that he was Abdullah ibn Amr. Husayn Salim Asad said that its chain of narration is good. It was also narrated by Abu Ubayd al-Qasim ibn Sallam in Fada'il al-Qur'an, and he said that the Mathna refers to the books of the People of the Two Books: the Torah and the Gospel.