The worshipers pumped their fists to the rhythm of the chant, the younger ones among them, including children, whipping their arms high above their heads.
"God is great!" came the refrain. "Death to America! Death to Israel! A curse upon the Jews! Victory for Islam!"
The crowd shouted it twice more in unison, before bowing their foreheads onto the thick carpet of the Bleily Mosque.
The slogan, spray-painted on walls and cinderblock throughout the Yemeni capital, has become the calling card of the Houthis, a Shiite faction that overran the Yemeni capital last year — and in recent weeks consolidated control of the central government. Critics call the move a coup.
The Houthi takeover has brought fears that Yemen — once touted by President Obama as a success of his counter-terrorism policy — could collapse, fall into civil war or disintegrate into warring regions. The country is home to Al Qaeda in the Arabian Peninsula, considered among the most dangerous branches of the global terrorist network.
The Houthis are sworn enemies of Al Qaeda. But they are also implacable foes of Washington and its regional allies, especially neighboring Saudi Arabia, a key U.S. partner that views Yemen as part of its sphere of influence and has a massive embassy here.
Last week, the United States and Saudi Arabia, among other nations, withdrew their diplomatic missions from the Yemeni capital. The U.N. called on the Houthis to relinquish control of the government.
Friday's sermon at a signature Houthi mosque provided some sense of the mood of defiance that has come to characterize the northern-based provincial power, which has vowed to destroy Al Qaeda and cut down on rampant government corruption. The fiery collective chant followed an equally blistering political broadside from the preacher, Faisal Atef, who lavished scorn upon Yemen's recent leadership, including U.S.-backed President Abdu Rabu Mansour Hadi, now under house arrest.
"Those leaders do not care about your concerns and pains!" said Atef, his eyes scanning the crowd before him. "All they care about is seven-star service."
The comments came only a few hours after Jamal Benomar, special United Nations envoy to Yemen, announced a "breakthrough" in U.N.-brokered negotiations while urging all parties to act "in the spirit of agreement."
The U.N. envoy said the talks were nearing a deal that would help resolve the nation's dire security and political crisis. He unveiled the creation of a new transitional council to run the country while negotiations on a comprehensive agreement continued.
The U.N. message hinted of reconciliation in Yemen's fractured and volatile political landscape. The scene at the Houthi mosque didn't suggest a mood of compromise.
The preacher accused rival factions of playing the role of a fifth column, singling out the Muslim Brotherhood's Islah (Reform) Movement as a corrupt party that had "mutilated" Islam.
He also railed against what he viewed as the meddling of regional and international entities, including the Arab League, the Saudi-led Gulf Cooperation Council and the U.N..
"When did the Arab League preserve the interests of Yemen? When did... the U.N. care for the interests of the Muslims, the Arabs and Yemenis?" asked the preacher.
Atef reserved special scorn for Saudi Arabia, which he accused of stoking conflicts among Yemen's tribes, the backbone of society here. Reports have suggested that Saudi Arabia has been arming anti-Houthi Sunni tribes.
"If Yemen came and tried to intervene in a decision in Saudi Arabia, would the Saudis remain silent? Or would they consider it a blatant intervention?" he asked in a thundering voice.
As the sermon came to an end and the worshipers gathered their sandals, they were reminded once more to join a pro-Houthi rally to take place later that day. Its slogan: "Against extortion and the American conspiracies and their agents... our revolution continues."