Boxing Champ Muhammad Ali is asking Iran to release two American hikers held since 2009 on spy chares.

Ali, arguably the most prominent US Muslim, released the letter he wrote to supreme leader Ayatollah Ali Khamenei to the Associated Press Wednesday.

The February 1st letter asks Khamenei to release Josh Fattal and Shane Bauer, who were arrested while hiking in northern Iraq near the Iranian border.

A third hiker, Sarah Shoud was released on bail in September, shortly after Ali first wrote to Khamenei. Ali’s letter asks Khamenei as a brother in Islam to show the same mercy and compassion for the two men.

Ali founded his center for world peace in Louisville, where he grew up and launched a boxing career that included three world heavyweight titles.