Thousands upon thousands of mourners took part in prayers during the second day of the funeral ceremony.
Mojtaba Khamenei has not appeared in public since the deadly attack that began the war in late February. He may have been injured in the same attack, but it is not known how serious his injuries were.
On Sunday, Khamenei's coffin will be moved from the stage where it has been on display since Saturday, before being taken in procession through the capital on Monday.
Television broadcasts show that President Masoud Pezeshkian has attended the ceremony along with other dignitaries, including Iran's chief negotiator Mohammad Bagher Ghalibaf.
Correction: An earlier version of the text stated the wrong time for the start of the war.
