Sayyiduna Anas bin Malik (may Allah be pleased with him) narrates that the Messenger of Allah (peace and blessings be upon him) went to the market and saw a heap of grain. He (peace and blessings be upon him) put his hand into it and brought out wet grain from underneath which had been struck by rain. He (peace and blessings be upon him) said to its owner: "What made you do this?" He said: "By the One who sent you with the truth! It is one and the same grain." He (peace and blessings be upon him) said: "Then why did you not keep the wet separately and the dry separately, so that people would buy (what they prefer) knowingly? Whoever deceives us is not of us."
Imam al-Tabarani (may Allah have mercy on him) said: "This hadith is narrated from Sayyiduna Anas bin Malik (may Allah be pleased with him) only with this chain, and Isma'il bin Abi Uways is alone in narrating it."