"I came back from the dead," the 37-year-old Palestinian, told AFP at a hospital in Bethlehem in the occupied West Bank.
Abayat, a butcher by trade, was arrested without explanation on October 26, just over two weeks after the unprecedented Hamas attack on southern Israel that sparked the Gaza war.
He was held at a prison in the Negev desert, officially under so-called administrative detention, which meant he could be held without charge or trial for an extended period.
"They arrested me at home, not surrounded by fighters but by my children and pregnant wife," said Abayat, whose sixth child was born while he was in jail.
Detentions of West Bank Palestinians have soared since the war began on October 7, with regular use of administrative detentions.
According to the Prisoners Club, a Palestinian watchdog, about 9,700 Palestinians are currently in Israeli jails, including hundreds under administrative detention.
The NGO estimates that arrests have doubled since October 7 compared to the same period last year.
Violence has surged in the territory since the start of the Gaza war, with at least 572 Palestinians killed by Israeli troops or settlers, according to the Palestinian authorities.
At least 16 Israelis have also died in Palestinian attacks, according to official Israeli figures.
In a video that went viral on social media when Abayat was freed Tuesday, he is seen limping and leaning on a man to walk, while his right hand seems paralysed.
'Not the same Muazzaz'
"No human being on the face of the earth can imagine how life has been" he said, calling the prison where he was held, "the 'Guantanamo of the Negev'", after the US prison in Cuba used to hold detainees after the September 11, 2001 attacks.
"We were unjustly detained, killed and severely beaten with iron clubs and subjected to all kinds of torture," Abayat added.
Israel's prison administration told AFP it was "not aware" of Abayat's claims.
"All prisoners are detained according to the law. All basic rights required are fully applied by professionally trained prison guards," an Israeli Prison Service (IPS) spokesperson told AFP.
"The prisoner was examined and treated medically by the IPS' finest doctors throughout his incarceration." The spokesperson said, Abayat could file a complaint if he wished.
Showing his bruised, bony legs, Abayat recounted beatings with clubs and chains, and said his body still hurt all over.
"They gave us 10 to 12 beans with pieces of cabbage, and we had to survive on that from 7.00 am until dinner time," he said while explaining his dramatic weight loss.
A "before and after" photo montage of Abayat shared online shows a muscular man with a shaved head and trimmed beard -- wildly different from the long dishevelled hair and messy beard of the man in the Bethlehem hospital.
"This is enough to tell what happened to me," he said of the photos.
His father Khalil Abayat told AFP that his son "was a man who weighed about 100, 110 kilos (220 to 242 pounds) and was muscular".
When Muazzaz stood on the hospital scale Wednesday, he weighed just 54 kilograms.
"When I saw Muazzaz, he was not the same Muazzaz my son was before his arrest," said the father, shocked by the confusion his son seemed to suffer from.
"He doesn't recognise me, he's disorientated and his health is very low."
Khalil added, however, that doctors had expressed confidence that Muazzaz's condition would improve. The former detainee has started eating more.
From his hospital bed, Muazzaz admitted that he had "forgotten things".
But he said he was not completely done with Israeli detention.
"I've left a small prison for the big prison" of Israel's occupation of the West Bank, he said.
