Musnad Ahmad 35:4

Isma'il narrated to us, Sa'id—meaning Ibn Abi 'Arubah—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], their transaction will be blessed. If they lie and conceal [the defects], the blessing of their transaction will be effaced."