It hadn't happened for eight years.
Iran's Supreme Leader Ayatollah Ali Khamenei making the main weekly sermon during Friday prayers in Tehran.
Addressing thousands inside a large prayer hall and many more outside, he said Iran's missile strikes on U.S. targets in Iraq showed it had divine support in delivering a "slap on the face" to a world power.
Iranians who'd gathered to watch his first sermon since 2012 chanted in sympathy "Death to America".
Khamenei described the retaliatory attacks - in response for America's killing of Iran's top military commander - as a "day of God".
In killing Qassem Soleimani, he told them the United States had showed its "terrorist nature".
And Khamenei warned that U.S. sanctions imposed in a row over its nuclear program would not make Iran yield.
The support shown here will surely have been met with some relief to Iran's clerical leaders.
At home and abroad, they have been under pressure after the military admitted to mistakenly shooting down a passenger airliner in Tehran earlier this month.
It happened in the tense aftermath of Iran's missile strikes on U.S. targets in Iraq, killing all 176 people on board.
Demonstrations against the downing of the airliner followed.
Footage posted online showed protesters being beaten and recorded gunshots, teargas and blood on the streets.
Iran's police denied firing at protesters.