Musnad Ahmad 125:4

Isma'il ibn Ibrahim narrated to us, Sa'id narrated to us, from Qatadah, from Abu al-Khalil, from 'Abdullah ibn al-Harith al-Hashimi, from Hakim ibn Hizam, who said: The Messenger of Allah (peace and blessings of Allah be upon him) said: "The two parties to a transaction have the option [to rescind or confirm] as long as they have not separated. If they are truthful and disclose [the defects], they are granted blessing in their transaction. But if they lie and conceal [the defects], the blessing of their transaction is wiped out."