Naji was born in Kirkuk, Iraq, on 1 December 1930 to his parents Eliyahu and Haviva. The family had nine children. The father was a merchant and the mother a homemaker. In 1933, the father made aliyah and the entire family, aside from the oldest brother, followed him a year later and settled in Jerusalem. The father then dealt in small merchandise while making a living in construction and contracting. The brother who had stayed behind in Iraq with the grandparents arrived in the Land of Israel only in 1953, after he had been imprisoned for his connections to family members in Israel.
Naji studied in the Doresh Zion elementary school in Jerusalem, but he did not complete his studies, going to work as a messenger boy. At ten he joined Beitar; at fifteen, Lehi, at his friends’ recommendation. He joined a cell of about eight dedicated to putting up posters and disseminating promotional materials. Later, he was trained with light weapons and explosives in the Ein Ganim orchard in Petah Tikva and transferred to the combat division. His activities there included attacking British armored vehicles with Molotov cocktails and planting bombs where British soldiers congregated. In one of these operations on Ben Yehuda Street, he and his comrade Binyamin “Immanuel” Barzani were surprised by a British patrol. Immanuel managed to rid himself of the Molotov cocktail and flee, but Naji was arrested. However, he was resourceful enough to slip away and mingle with the crowd leaving the nearby cinema. The British blew up the Molotov cocktail by shooting it.
About the time of the War of Independence, he was training at Sheikh Badr. He and his comrades were attacked by the British with gunfire and grenades; one of the instructors, Mishael, was injured in his chest. He found refuge at a Naveh Shaanan home and was retrieved that night by Lehi. Naji and his other friends managed to escape thanks to a Jewish Settlement Policeman.
During the war, he was active in the Lehi camps in Jerusalem, participating in the attacks on Der Yassin, the Old City and Notre Dame. After the capture of Der Yassin, he was part of the force which escorted the women and children evacuated to the Old City.
In 1949, he enlisted in the IDF, serving in the Artillery Corps. He was discharged six months early due to his Lehi service.
In 1953, he married Dina Zedekiah and they had three daughters and numerous grandchildren. Until 1955, Naji worked in construction; later, he started working for an insurance fund for construction workers under the auspices of the Histadrut. He retired in 1988.