Allah excused, during that [time], those with physical disabilities, and said: 'There is no blame upon the blind, nor is there any blame upon the lame'—meaning sin—'nor upon the sick'—for them to stay behind from the military expedition. Thus, it became a concession for them in regard to military expeditions, and [the obligation] was removed from them.

Interpretation of Surah al-Fath from verse 18 to verse 23.