Narrated Hakim bin Hizam:
The Prophet said, "The buyer and the seller have the option of cancelling or confirming the bargain unless they separate, and if they spoke the truth and made clear the defects of the goods,...
O Allah, praise is to You. You have clothed me. I ask You for its goodness and the goodness of what it has been made for, and I seek Your protection from the evil of it and the evil of what it has been made for.
Info: Abu Dawud and At-Tirmidhi. See also Al-Albani, Mukhtasar Shamd'il At-Tirmidhi, p. 47.