Hazrat Khalid al-Neeli narrates that Hazrat Hakam and Hazrat Hammad gave a ruling about a man who injured another man's head and as a result, his eyesight was lost. Upon this, Hazrat Hammad said: If people testify that his eyesight was lost due to the blow, then it is permissible. And Hazrat Hammad said: If people testify that on the day he was struck, his eye was sound, then in this case it is permissible.