Sheikh Raed Salah, the head of the Islamic Movement in Israel, has turned himself in to Israeli authorities to start a five-month jail sentence.
Salah was convicted of assault for an incident that took place in 2007 during a demonstration in occupied East Jerusalem, in which court documents suggested he insulted a border policeman and spat in his face.
The sentence was nine months initially, but reduced to five months by a Jerusalem court earlier this month. Salah has always denied the charges.
"We are going to jail today in defence of al-Quds (Jerusalem). It would not surprise us if Israel divide Jerusalem by force," Salah told a crowd in front of his prison on Sunday.
The alleged assault reportedly took place during a protest outside the Dung Gate in the southern wall of the Old City where the Israeli authorities were carrying out restoration work near the al-Aqsa mosque compound.
The compound is the third holiest site for Muslims and the holiest site for Jews, who refer to it as the Temple Mount. It has been the scene of several outbreaks of violence over the course of the decades-old Israeli-Arab conflict.
Last May, Sheikh Raed Salah, was acquitted by a Jerusalem court in connection with rioting in the city three years ago. The court found the charges against him were inconsistent with witness testimony and video evidence produced by defence. The court also found him not guilty of involvement in an illegal gathering.
Salah has been detained on a number of occasions, most recently after taking part in a Gaza-bound aid flotilla stormed on May 31 by Israeli naval commandos in an operation which left nine Turkish activists dead.
Israel's Arab community numbers 1.3 million, about 20 per cent of the population. It is made up of descendants of the 160,000 Palestinians who remained in Israel after the 1948 establishment of the Jewish state.
Arab Palestinians during the British mandate and before the creation of Israel numbered close to two million.