Sayyiduna Abdullah bin Abbas (may Allah be pleased with them both) narrates this statement of the Noble Prophet (peace and blessings be upon him): "When a person buys something, it becomes binding upon him, and he has the right regarding it over his companion until he separates from him. If he wishes, he may take it, and if he wishes, he may leave it. But if he separates from his companion, then he will no longer have any choice."
Hadith Referenceصحیح ابن حبان / كتاب البيوع / 4914
Hadith Gradingفضيلة الشيخ الإمام محمد ناصر الدين الألبانيحسن صحيح - «أحاديث البيوع».فضيلة الشيخ العلّامة شُعيب الأرناؤوطإسناده حسن