He made the remarks in ceremony to establish Iraqi Assembly of Islamic Unity in Baghdad.
'No sin is bigger than sowing discord among Islamic Ummah,' Araki added.
He praised the role of religious authorities in strengthening Islamic unity in Iraq and victory on Takfiri group of Daesh.
The ayatollah also appreciated cooperation of Iraqi President Fuad Masum and Prime Minister Haidar al-Abadi in establishment of the assembly.
Iraqi Assembly of Islamic Unity was opened in Baghdad on Saturday in the presence of Sunni and Shiite characters from Iraq and other Islamic states and by participation of Supreme Leader Aide for international affairs Ali Akbar Velayati.
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