Hadeeth: 'When you see the black flags…'
8-12-2014 | IslamWeb
Question:
ASSALAM ALEIKUM I WAS INQUIRING ON THE AUTHENTICITY OF THIS HADITH "It is related on the authority of ‘Ali ibn Abi Talib (may Allah ennoble his countenance): ‘When you see the black flags, remain where you are and do not move your hands or your feet (It’s a common phrase meaning: “Stay put and don’t get involved in the fighting”). Thereafter there shall appear a feeble folk to whom no concern is given. Their hearts will be like fragments of iron. They are the representatives of the State (As-hab al-Dawla). They will fulfill neither covenant nor agreement. They will invite to the Truth, though they are not from its people. Their names will be agnomens [i.e., Abu Mus'ab, Abu Bakr, etc.], and their ascriptions will be to villages (or places) [i.e., al-Misri, al-Harrani, al-Baghdadi, etc.]. Their hair will be long like that of women. [They shall remain so] till they differ among themselves, and then Allah will bring forth the truth from whomever He wills." Kitab Al Fitan (Book of Tribulations) by Nu'aym ibn Hammad
Answer:
All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad, sallallaahu ‘alayhi wa sallam, is His slave and Messenger.
The statement which you mentioned is not a Marfoo‘ Hadeeth (traced back to) the Prophet, sallallaahu ‘alayhi wa sallam, but it was a statement of ‘Ali 
and it was reported by Nu‘aym ibn Hammaad in Kitaab Al-Fitan.
We found that none of the prominent scholars assessed whether it is authentic or weak. However, some contemporary scholars criticized its chain of narrators because it contains some narrators who have been criticized, among whom was Ibn Lahee‘ah as a Hadeeth narrated by him is weak except if it was reported from him by ‘Abdullaah ibn al-Mubaarak or ‘Abdullaah ibn Wahb or ‘Abdullaah ibn al-Muqri’ because if they reported a Hadeeth which was narrated by him, then it is authentic as clarified by the scholars. This statement was not narrated by any of them. Moreover, its chain of narrators includes Rashdeen ibn Sa‘d, and the Ahaadeeth he reports are weak in the view of the scholars of Hadeeth.