Thousands of pilgrims have arrived in the holy city of Najaf, Iraq, on the eve of Arba’een procession which marks 40 days after martyrdom anniversary of Imam Hussein (AS), third Shia Imam and grandson of Prophet Mohammad (PBUH) who sacrificed his life to fight against tyrant ruler of his time, Yazid ibn Muawiyah in the Battle of Karbala back in 680 AD.