Wafa Sarhan was devastated to think her two sons would never hear her voice again after an Israeli strike on Gaza rendered them deaf.
Then Dr. Hajeri showed up in the impoverished enclave.
Bahaa and Qusei Sarhan, today six and five, lost their hearing in June 2004 when an Israeli drone fired missiles at a group of militants near their home in the northern town of Jabaliya.
"Bahaa was wounded again by shrapnel during the last war (in December and January) because there was shelling and he couldn't hear us yelling at him to come inside," she says.
Since the boys lost their hearing, Wafa Sarhan and her husband have been trying to get them treated outside the coastal strip, which Israel and Egypt have kept under a tight blockade since the Islamist Hamas movement seized power in June 2007.
They heard of a procedure under which a device dubbed an electronic "snail" is inserted in the ear, enabling a person to regain his hearing.
But the only place in the Arab world where the procedure is available is a medical centre in the United Arab Emirates (UAE), which charges 60,000 dollars (40,000 euros) for the operation.
"If we gave them everything we own it would not cover a fourth of the price," she said.
Then, last week, Mazen al-Hajeri, a doctor from the UAE specialising in the procedure, showed up to do a string of the operations for free in the Gaza Strip, where scores of children have lost their hearing as a result of Israeli operations over the years.
"We came to help the children here who cannot hear and we donate our services to whoever we can help," he says, sipping water in a break between operations carried out at a remorseless pace from 9am to 10pm each day.
Hajeri says he was motivated to come to Gaza during last winter's war, when satellite news showed non-stop footage of heavy shelling and terrified civilians huddling in shelters across the densely populated territory.
And so Wafa Sarhan found herself waiting outside the surgery room at the Al-Shifa hospital in Gaza City, her face twisted with worry as other doctors tried to reassure her that everything would be alright.
Two hours later, it was.
"Today my children have been born again," she says, all smiles after the operations turn out to be successful. "I am so happy. We were very frustrated and did not know what to do."
A line of waiting families stretched outside the operating room as Hajeri performed one operation after another, working 13 hours a day with only short breaks between procedures.
By the time he left on Sunday, Hajeri had performed around 50 operations on children suffering from hearing loss, a quarter of them because of war, but plans to return in several months time to carry out more as well as train local doctors.
The UAE Red Crescent Society last week inaugurated a centre for hearing in Gaza complete with supplies and modern medical equipment with the agreement of Salih al-Tai, the director of relief and emergencies for the society.
"This centre is the first of its kind in the Middle East," said Tai, who declined to comment on how much money had been invested.
"Doctor Mazen is training Palestinian doctors to carry out operations... and he will come every two months to follow up and to carry out similar operations."
Not all were lucky enough to get one of the coveted spots.
Twenty-six-year-old Sahila cried when she found she couldn't get her only child onto the list for surgery -- there were simply too many other patients for the available time.
"Where are the Arabs who can help us?" she said as she sobbed outside the surgery ward.
Hossam Aqel, 37, was one of the lucky ones.
His two-year-old son was wounded when there was shelling near his house during this year's war.
"After two months we discovered that he could not hear or make sounds and when we took him to the doctor he said he had lost his hearing," he said, adding that he also could not afford the 60,000-dollar fee because he has been unemployed for several years.
"Thank God, this is the happiest day I have ever had," he said. "I can see that my son can hear and will be able to talk like the others."