Iran’s supreme leader has been seen weeping over the remains of Qasem Soleimani days after the top general was killed in a US air strike in Baghdad.
The targeted killing of the Iranian Revolutionary Guard General has already seen the country vow to take revenge.
Supreme Leader Ayatollah Ali Khamenei prayed over the caskets of General Soleimani and others slain in the attack.
Mr Khamenei, who had a close relationship with the general, wept at one point during the traditional Muslim prayers for the dead amid wails from a crowd of hundreds of thousands of mourners.
People cried while others clutched pictures of the late commander. Mourners passed his coffin over their heads and "death to America" chants were heard.
General Soleimani's daughter has warned the US it faces a "dark day" for the killing.
"Crazy (President) Trump, don't think that everything is over with my father's martyrdom," she said.
To cheers she added: “The families of the American soldiers in western Asia… will spend their days waiting for the death of their children."
While Iran recently faced nationwide protests over government-set petrol prices that reportedly killed over 300 people, General Soleimani’s mass processionals has seen politicians and leaders across the Islamic Republic’s political spectrum temporarily silencing their anger to take part.
During the prayers, the general's successor Esmail Ghaani stood near Mr Khamenei’s side, as did Iranian President Hassan Rouhani and other top leaders in the Islamic Republic.
General Soleimani was hailed as a national hero in Iran and widely considered the second most powerful man in the country behind the Supreme Leader.
The US saw him as a terrorist, and President Donald Trump justfied the killing by saying General Soleimani was plotting "imminent" attacks on US diplomats and military personnel.
Tehran has abandoned the remaining limits of its 2015 nuclear deal with world powers in response to the slaying while in Iraq the parliament has called for the expulsion of all American troops from Iraqi soil.
The developments could bring Iran closer to building an atomic bomb, set off a proxy or military attack launched by Tehran against the US and enable the Islamic State group to stage a comeback in Iraq, making the Middle East a far more dangerous and unstable place.
Adding to the tensions, Mr Trump threatened to demand billions of dollars in compensation from Iraq or impose “sanctions like they’ve never seen before” if it goes through with expelling US troops.
