"Look, see, what Assaf is doing!" young men in Gaza chanted in unison, as other people honked and set off fireworks.
It's just the second year of the show, modeled on American Idol. Assaf's victory after the final round of competition Friday night provided a rare moment of unity among Palestinians, focused on music and joy.
Doaa Abu Ghanemah, 23, said she felt close to tears when Assaf won.
"First of all, Mohammad Assaf is from my country," she said Saturday night, in the middle of a Gaza City street packed with noisy Assaf supporters. "He shows that Palestine is not only a country of wars and battles. Palestine has talent, genius and nice singers."
But for many, Assaf's victory is as much about politics as it is about pop culture.
"Palestinians have been looking for a nonpolitical role model for a long time, this is the reasons why Mohammd Assaf victory was huge," wrote Palestinian journalist Daoud Kuttab on his Twitter account.
Other comments on Twitter said Assaf has united Palestinians in a way political leaders have failed to do. Political leadership among Palestinians has been divided since 2007, when Hamas won power in the Gaza Strip. The Palestinian Authority remains in control of the areas in the West Bank, where Palestinian civil governance is allowed to operate.
In the final weeks of competition, Palestinian President Mahmoud Abbas told Palestinian diplomats to encourage expatriates to vote for Assaf. After Assaf's victory, he was reportedly promised a Palestinian diplomatic passport and named a youth ambassador.
Victories by the other two finalists — Ahmed Jamal from Egypt and Farah Youssef from Syria — could have also carried political overtones, as they come from countries torn by internal divisions.
Assaf was born to Palestinian parents in Libya, where his father worked at the time. He returned to Gaza with his family when he 5 years old. He first sang in public soon after, at a local event that former Palestinian leader Yassar Arafat attended. As a university student, Assaf earned money by singing at weddings.
To get into the Arab Idol competition, he had to audition in Egypt, but delays at the border from Gaza made him late to the tryouts. His family says he jumped the fence at the hotel where the auditions were held. He didn't have an audition number, but a fellow Palestinian Ramadan Adeeb Abu Nahel heard him warming up and offered Assaf his audition spot.
"I decided to give him my number because he is a fabulous person," Abu Nahel told NPR before the final round of Arab Idol. "At first he wouldn't take it, but a relative who was with him and I insisted."
He says Assaf told him at the time that he would never forget the favor. Many Palestinians will never forget this night.
Salem Jabber, 29, celebrated Saturday night in Gaza, where borders are controlled by Israel and Egypt, and imports and travel are restricted.
"We don't have gasoline, we have no good drinking water," Jabber said. "Assaf is the good thing here. That's why we are happy despite the siege."