What is "as-saffah"

Abu al-‘Abbās ‘Abdu'llāh ibn Muhammad as-Saffāḥ, or Abul `Abbas al-Saffaḥ (b. 721/722 AD – d. 10 June 754) was the first caliph of the Abbasid caliphate, one of the longest and most important caliphates (Islamic dynasties) in Islamic history. (Due to different traditions of transcribing Arabic names, the spellings As-Saffah and Al-Saffah may both be found.)

As-Saffāḥ is a messianic religious title from hadith literature on the mahdi, which, in older Arabic, meant the Generous from the Arabic verb yasfaḥ, "to pour out," implying the future ruler would be liberal in dispensing wealth to Muslims. (In Modern Arabic this word has taken a negative connotation: One who pours out blood/thug). The new caliph appropriated this messianic title in his first sermon in Kufa in 749 AD. A weaker alternative explanation of the title is slaughterer or shedder of blood for his ruthless efforts to eliminate the rival Umayyad family - unlikely, however, since no caliph would have appropriated the title for himself if that were the original meaning.