Sayyiduna Abdullah bin Umar (may Allah be pleased with them both) narrates: Sayyiduna Munqidh (may Allah be pleased with him) (he was an Ansari companion) had received a head injury in the pre-Islamic era, due to which he developed a stutter in his tongue. When he used to make a transaction, he would be deceived during the transaction. The Prophet Muhammad (peace and blessings be upon him) said: "When you make a transaction, say that there will be no deception. Then you will have the option (to cancel the deal) for three days." Sayyiduna Abdullah bin Umar (may Allah be pleased with them both) says: I heard him making a transaction; he was saying «لا خذابة» (i.e., due to his stutter, he pronounced 'lam' as 'dhal').