Mohammed Nazzal, a senior Hamas leader based in Damascus, challenged Arab governments to "open their borders and allow the fighters to come."
Delegates from all over the Middle East, and from Somalia, Sudan, Pakistan and Indonesia applauded as he stabbed the air with a raised finger and declared: "There will be no agreement with Israel... only weapons will bring respect."
Aftermath of Israeli bombing of Gaza
Gaza has opened a gulf between Arab people and their regims, the clerics say
Mr Nazzal told his audience: "Don't worry about casualties."
The 23 days of bombardment of Gaza, in which some 1,300 people, many of them civilians and nearly 300 of them children, are believed to have died, was "just the beginning" of the struggle, Mr Nazzal said.
To laughter in the audience, another speaker noted that twice as many babies were born as children were killed during the war.
Every death, I was told, was a martyrdom on the road to liberation.
Hat Tip Little Green Footballs