Fraud and deception are also forbidden in Islam. This would include intentionally concealing defects in one’s merchandise or work. One time the Prophet (peace be upon him) was in the marketplace and he put his hand into a pile of grains and he found that it was wet on the bottom. He asked the vendor about it and the man told him that rain had fallen upon it. So the Prophet (peace be upon him) told him, “Why did you not put it on top of the grain so people could see it? Whoever deceives is not from me.”

Ibn Maajah records that the Prophet (peace be upon him) said in another hadith stressing the aspect of brotherhood and its relation to business dealings, “A Muslim is a brother to a Muslim. It is not permissible for a Muslim to sell something defective to his brother without making that [defect] clear to him.”