The families of two U.S. hikers being held in Iran on spy charges are hoping that Muhammad Ali still packs a punch in international diplomacy. Ali, one of the highest profile Muslims in the U.S., wrote a letter asking Iranian supreme leader Ayatollah Ali Khamenei to release the hikers — held since 2009 as suspected spies. The letter, written in February, was released on Wednesday by the Associated Press.

The letter asks Khameini to release Josh Fattal and Shane Bauer, who were arrested while hiking in northern Iraq near the Iranian border. A third hiker, Sarah Shourd, was released on bail in September.

“Please show the world the compassion I know you have in your heart,” he wrote, asking Khamenei as a brother in Islam to show the same mercy and compassion for the two men as he did for Shourd.

Ali also wrote a letter to Khamenei shortly before Shourd was released, though it was unclear whether it had any effect.

Not that it necessarily means anything — although it could — but boxing is pretty big in Iran. Fun fact: Emmanuel Agassi, father of Andre Agassi, represented Iran as a boxer in the 1948 and ’52 Olympics.

Despite being diagnosed with Parkinson’s disease in 1984, Ali had traveled the world in support of humanitarian causes since his retirement from boxing. One of the most famous was his 1991 trip to Iraq during the Gulf War to meet with Saddam Hussein to try and negotiate the release of American hostages.

As great a boxer as he was, Ali has proven since retirement to be an even better man. Talk about your role models, this is the real deal, kids.