In a message to Iraqi President Barham Sailh and Prime Minister Adil Abdul Mahdi, released on Sunday, Rouhani said the huge and magnificent Arbaeen march held in Iraq with the participation of millions of Imam Hussein (AS) devotees once again conveyed the message of Ashrua to the world.
He added that the great annual world gathering is a manifestation of unity and solidarity among Muslims, and especially the Iranian and Iraqi nations.
Rouhani also thanked the Iraqi authorities, senior scholars and people who served the Arbaeen pilgrims with hospitality and provided full security.
Arbaeen comes 40 days after Ashura, the martyrdom anniversary of the third Shia Imam, Imam Hussein (AS).
Each year, a huge crowd of Shias, including many Iranians, flock to the Iraqi city of Karbala, where the holy shrine of Imam Hussein (AS) is located, to perform mourning rites.
Arbaeen fell on Saturday, October 19, this year.