Is the Hadith: "Days and nights will not pass until Allah raises from us, the Family of the Prophet (Ahl al-Bayt), a young, youthful, new man who will establish the affair of this nation" authentic, and does it refer to the Mahdi or someone else?

This narration, mawquf to Ibn Abbas, may Allah be pleased with him, was transmitted by Al-Khallal. In it, Ibn Abbas said: "I hope that days and nights will not pass until Allah raises from us, the Ahl al-Bayt, a young man whom tribulations have not worn out nor has he worn out tribulations. Just as Allah opened this matter through us, I hope He will conclude it through us." Abd al-Rahman ibn Mahdi authenticated this report, and that the mentioned young man is the Mahdi. Ibn Kathir mentioned the report in Al-Bidaya wa al-Nihaya and said: "This is a sound chain of narration to him."