For weeks, Mustafa Abutaha wandered the halls of one of Gaza’s few functioning hospitals and filled his days by volunteering to do whatever was needed — sweeping floors, baking bread, dressing injured patients, feeding dates or tomato sandwiches to those who couldn’t feed themselves. Anything to avoid thinking about his son, Muhammed.

As the Israeli military targeted the southern city of Khan Younis in early December and fighting with Hamas intensified, his family’s home was struck while he was visiting a neighbor, Mr. Abutaha said. His brother was killed. Three of his five children were injured. And Muhammed, 18, was found motionless in a stairwell.

“If somebody sends me his picture, I just shout at him and say: ‘Please don’t remind me of my son. He’s already dead. Please, I don’t want to bring back memories,’” Mr. Abutaha said. “Oblivion, forgetfulness, is a blessing from God.”

Soon after the strike, he said, he and his family fled to Nasser Hospital in Khan Younis, at the time one of the last facilities in the Gaza Strip still offering medical care and shelter to the displaced. Now, its operations are in peril.

This week, Israeli forces ordered the evacuation of the thousands of civilians sheltering at Nasser and, on Thursday, began a raid against what it says is Hamas activity inside the hospital. Hundreds of patients, staff members and displaced Palestinians had already fled, including Mr. Abutaha, though many remained.

Beginning in December, Mr. Abutaha, a professor of English, sent dozens of voice and video messages to The New York Times providing an unusually direct window into the struggle to survive inside an embattled Gaza hospital.

“Our situation is unbearable,” he said in one of the messages. “We can’t endure anymore.”

Blow by blow, the war in Gaza has dismantled Mr. Abutaha’s life, as it has for so many others in the territory of about 2.2 million Palestinians.

His university was shuttered by the fighting and it is unclear whether it will ever reopen. His wife managed to take his surviving children to Egypt for medical treatment, but it is not clear whether they will fully recover, he said. (His fifth and eldest child left the country before the war). He doesn’t know when he will see them again. He has tried to rejoin them, he says, but Israel and Egypt have made it extremely difficult to leave.

With nowhere to go after the strike on his home, Mr. Abutaha, 47, volunteered at the hospital, where he took advantage of the relatively reliable internet — a rarity in Gaza — to communicate with The Times. He connected reporters with hospital staff members and patients and shared videos, voice memos and texts showing the grim conditions.

Doctors struggling with scarce supplies. Displaced people sleeping in hallways. Hunger gnawing as food grew scarce. Casualties pouring into the hospital wards.

The war began after the Hamas-led Oct. 7 attack on Israel that, Israeli officials say, killed about 1,200 people. Israel responded with heavy bombardment of Gaza and a ground invasion that have devastated the small coastal enclave, killing an estimated 28,000 people, displacing most of the population and setting off a humanitarian catastrophe.

Israel has accused Hamas, which gained control of Gaza in 2007, of using hospitals for its military operations, turning them, the Israelis claim, into legitimate military targets. The Israelis have ordered evacuations from a number of hospitals, and Israeli soldiers raided some of them.

Hamas and hospital administrators have previously denied the Israeli claims. Classified Israeli intelligence reviewed by The Times suggests that Hamas operated under a major hospital, Al-Shifa, but it falls short of proving Israel’s early contention that there was a command center there.

In his many messages from Nasser Hospital, Mr. Abutaha condemned Israel for its assault on Gaza.

But in conversations with The Times in recent months, he also criticized Hamas, sentiments rarely expressed publicly in Gaza during the war, in part for fear of retribution by the militant group. During the 2014 Gaza war, Mr. Abutaha wrote a handful of online posts that painted Hamas in a positive light, but now he suggested that the Oct. 7 attack had needlessly endangered Palestinians. And he said he opposed violence, including that attack.

“Lots of people cursing Hamas, cursing the leaders,” he said in a voice message, speaking English. “Hamas started the war,” but we are “the victims of this war.”

Mr. Abutaha’s video messages showed more people seeking shelter in the hospital each day, hanging laundry from the windows, sleeping in the hallways and stringing up sheets for a modicum of privacy. In the orthopedic ward, displaced Gazans struggled to find space inside a complex that was never meant to house so many people.

Without enough to eat, Mr. Abutaha noticed one day that he could see his clavicles for the first time in years.

“You see the bones?” he said in one video.

When he couldn’t find coffee, he poured hot water over burned toast or crushed date pits, just to have some black liquid to drink.

When aid convoys reached the area, people lined up for whatever they could grab, said Haneen Abu Tiba, 27, one of the people sheltering at the hospital whom The Times connected with through Mr. Abutaha.

Sometimes, chaos broke out and people pushed and shoved, she said, as Hamas’s security forces did little to keep order. She said she had fled airstrikes in her neighborhood with her mother and sisters.

In January, Mr. Abutaha and his cousin got an aid package and shared a video of the box’s contents: two kilograms of dates, 10 cans of beans, two kilograms of sugar and five kilograms of rice.

It seemed like a bounty at a time when hunger is so widespread.

Mr. Abutaha recounted how he had saved for years to build his four-story house in Khan Younis and had hosted Westerners who came to Gaza on humanitarian missions.

Now, the house is a shell of rubble and twisted metal, he said.

On the day that changed the family’s life forever, Mr. Abutaha’s wife, Reem, had left to run an errand right before their home was struck, she said in an interview. In the chaos, it was not clear where Muhammed’s body had been taken.

Ms. Abutaha barely made it to the graveyard in time to find neighbors burying him, she said.

At the hospital, a close friend of Mr. Abutaha’s, Dr. Ahmed al-Farra, who ran Nasser’s pediatric ward, treated those wounded in the strike.

“This was the worst day of my life,” Dr. al-Farra said in an interview. “The E.R. was full of blood and injured children and injured patients, and there weren’t enough doctors to help them.”

Mr. Abutaha’s daughter, Leyan, 14, had a brain injury that left her in a coma for a month and a half, her mother said. Another son, Abdul Aziz, 16, had a skull fracture, a broken jaw and a crushed foot. Yamen, 6, had a thigh wound and burns.

Every time Mr. Abutaha speaks with his wife in Egypt, she begs him to come help her care for their children in the unfamiliar country. He tells her he is trying.

Last month, fearing for his safety as the Israeli military approached the hospital, Mr. Abutaha fled with a handful of doctors. He is now living in a tent in al-Mawasi, an area with little infrastructure that has become overcrowded with displaced Gazans.

He said he has developed a bad cough, and with little water or soap for bathing, he has taken to swimming in the sea and rubbing his body with sand to get clean.

Mr. Abutaha is still trying to stay busy, he said, but there is not much to do, and so the memories keep coming back.

“I can’t forget,” he said.

He has deleted the photos of his dead son from his phone.

Video production by Axel Boada.