Sahih Muslim Book 4, Hadith Number 2005.

Chapter : Closing the (eyes) of the dead and supplication for him on visiting him.

Abu Huraira reported Allah’s Messenger (may peace be upon him) as saying: Did you not see when the man died and his eyes were fixedly open? He (Abu Huraira) said: Yes. He (the Holy Prophet) said: It is due to the fact that when (the soul leaves the body) his eyesight follows the soul.