IRNA � President Hassan Rouhani on Sunday thanked the Iraqi president and prime minister and religious leaders for hosting Arbaeen pilgrims.

In his message to Iraq's President Barham Salih and Prime Minister Adil Abdul-Mahdi, President Rouhani said that millions of people attended the Arbaeen Walk this year, which shows the congregation is not just a matter of history, but, an eternal historical miracle and the strongest media for introducing the tragedy of Ashoura.

President Rouhani said that the annual ceremony is actually the manifestation of solidarity and closeness of Iran and Iraq and formation of one united front against discrimination and violence.

It is necessary to thank the officials and religious Leader of Iraq who spared no efforts to provide full security for the guests, he added.

Arbaeen, an Arabic word meaning the 40th, is a mourning ceremony held 40 days after Imam Hussein (AS), the third Imam of Prophet Muhammad (Peace Be Upon Him) Infallible Household and his 72 companions, including 18 of family members and close relatives, were brutally martyred in Karbala on Ashura, the 10th day of the lunar month, by the army of the second Umayyad caliph, Yazid, in AD 680.

The mourning ceremony began and was soon established when Jabir ibn Abdollah Ansari, a close follower of Prophet Mohammad (PBUH), then 77, visited the grave of Imam Hussein (AS0 as the Imam's first pilgrim, 40 days after Ashura.

More than three million Iranian attended this year's ceremony.