Sayyiduna Abdullah bin Umar (may Allah be pleased with them both) narrates: A man was mentioned before the Prophet (peace and blessings be upon him) who used to be deceived in business transactions. The Prophet (peace and blessings be upon him) said: When you buy or sell something, say: "No deception will be tolerated." The narrator says: So when that man would sell something, he would say: "No deception will be tolerated."