Sahih Muslim Book 8, Hadith Number 3318.

Abu Salama b. ‘Abd al-Rahman reported: I asked ‘Aisha, the wife of Allah’s Messenger (May peace be upon him): What is the amount of dower of Allah’s Messenger (May peace be upon him)? She said: It was twelve ‘uqiyas and one nash. She said: Do you know what is al-nash? I said: No. She said: It is half of uqiya, and it amounts to five hundred dirhams, and that was the dower given by Allah’s Messenger (May peace be upon him) to his wives.