The Messenger of Allah ﷺ passed by a man selling food. He put his hand into it and found that it had been tampered with. The Messenger of Allah ﷺ said, "Whoever cheats is not one of us."
حدثنا هشام بن عمار حدثنا سفيان عن العلاء بن عبد الرحمن عن أبيه
مر رسول الله ﷺ برجل يبيع طعاما فأدخل يده فيه فإذا هو مغشوش فقال رسول الله ﷺ ليس منا من غش
[Its chain of transmission is sahih] Abu Dawud narrated it in the Book of Business Transactions, chapter on the prohibition of fraud, hadith no. 3452, from the hadith of Sufyan bin Uyayna, with this chain, and Hakim graded it sahih in 2/98 according to the criteria of Muslim, and Dhahabi agreed with him. Muslim narrated it, hadith no. 102, and others as well, from Ismail bin Jafar, from Ala, with this chain, conveying a similar meaning.