The Banu Sa'ida (Arabic: بنو ساعدة, romanized: Banu Sā'idah) was a clan of the Banu Khazraj tribe of Medina in the era of Muhammad. The tribe's full name was the Banu Sa'ida ibn Ka'b ibn al-Khazraj.
Prior to their conversion, most members of the clan worshiped idols, which were destroyed after the advent of Islam. Their Jewish allies or clients are mentioned in the Constitution of Medina.
The Saqifa (Arabic: سَقِيفَة, romanized: Saqīfah) of the Banu Sa'ida clan refers to the location of an event in early Islam where some of the companions of the Islamic prophet Muhammad pledged their allegiance to Abu Bakr as the first caliph and successor to Muhammad shortly after his death in 11 AH (632 CE). The Saqifa meeting is among the most controversial events in early Islam, due to the exclusion of a large number of Muhammad's companions, including his immediate family and notably Ali, his cousin and son-in-law. The conflicts that arose soon after Muhammad's death are considered to be the main cause of the current division among Muslims. Those who accepted Abu Bakr's caliphate were later labeled Sunnis, while the supporters of Ali's right to caliphate were later labeled Shia.