The attorney, Mohammed Jabareen, spoke Monday after the deal was struck at an Israeli prison clinic. Israeli prison officials could not be reached for comment.
The soccer player, Mahmoud Sarsak, has been held by Israel for nearly three years without charges or trial. Israel claims he was active in the violent group Islamic Jihad. Sarsak denies the allegations.
As his condition worsened, prominent figures in the sports world came to his support. FIFA's president asked Israel's soccer federation for help and FIFPro, an international organization of footballers, called for his release.