Chris Eubank Jr. says Nick Blackwell's decision to risk sparring after a life-threatening head injury was "absolute madness".
The 26-year-old needed an emergency procedure to reduce brain swelling following an unsanctioned sparring session last month; he remains in hospital but has emerged from a coma.
Blackwell had been forced into retirement in March after he collapsed following his stoppage defeat to Eubank, when a bleed on the brain was discovered.
"It's just madness, absolute madness," Eubank said of the episode. "I understand how strong a love can be for the sport because I have that love inside me. But there is a difference between loving your sport and being able to spend time with your family and enjoy life.
"That is what he risked when he had that sparring session. It's a shame but hopefully he pulls through again, everything is fine, and he can learn from his mistake."
Hasan Karkardi and Liam Wilkins, the fighter and trainer involved in the sparring session that injured Blackwell, have since been suspended by the British Boxing Board of Control.
But there have been issues between the Eubank and Blackwell families since the fight.
Eubank was discouraged from visiting Blackwell in hospital because the fighter's family were unhappy at their conduct during a post-fight news conference, and the relationship between the two camps deteriorated.
"The last time I tried to be there and I wanted to see him [Blackwell] but everyone around him blocked it," said Eubank, who has begun preparations for his super-middleweight fight against IBO champion Renold Quinlan on Feb. 4.
"Then he came out of the coma and said the things he said about me and my father so I've kind of got the message to just leave it. But I'd love to see him again and shake his hand."