"The piece of bone is in a bad position and the doctors told me it was too dangerous to operate. They told me that only time will be the healer now."
Six weeks ago Mr Kahui was forced to leave his rented house in Auckland after it was sold so he sent Manutahi and his daughter to stay in Wanganui.
"I have been trying to get a Housing Corporation house. I thought I would get one within weeks so I sent Manutahi and my small daughter to stay with their older sister and brother in Wanganui until a house came through."
On Wednesday, Mr Kahui got the phone call telling him his son had been stabbed.
"What a terrible day, a really terrible day for our family."
Mr Kahui said he was thankful he was able to stay at Ronald McDonald House while he is in Wellington.
"Because Manutahi is 16 we are able to stay there ... it is pretty wonderful for us and we really appreciate it."
He admitted that some of the family were gang members but not Manutahi.
"He is a quiet and special boy who doesn't belong to any gang."
Mr Kahui is a Black Power member and two of his other sons are members of the Tribesmen, but he stressed that Manutahi was not associated with any gang.
"He's a big 16-year-old but he's just a big kid really, a big gentle, kind kid."
Mr Kahui said as far as the case goes it rests entirely with the police.
Detective Sergeant John Gleeson said inquiries were continuing and police were still visiting properties throughout the area and talking to people.
Whanganui Detective Sergeant Dave Kirby said police were still looking for a male Maori, 1.83m (6ft) tall, with a number one haircut. He is believed to have beige pitbull with him.