Musnad Abu Ya'la al-Mawsili 154:193

On the authority of Ibn Umar, that the Messenger of Allah (ﷺ) said: "The two parties to a transaction have the option (to rescind) as long as they have not separated, each of them having an option over the other, unless it is a transaction of option." Malik said: "There is no known limit for this according to us, nor is there a matter practiced regarding it."