The Messenger of Allah ﷺ said, "Do not engage in najsh."
قال رسول الله ﷺ: لا تناجشوا.
No references are available.
Abu Dawud (3438) narrated it from Ahmad bin Amr bin Sarh, who said, Sufyan told us, from Zuhri, from Saeed bin Musayab, from Abu Hurairah, as mentioned. From this same chain, it was also recorded by Tirmidhi (1304), Nasai (4506), and Ibn Majah (2174), each adding something to the others, except that Nasai narrated it through the route of Mamar, from Zuhri. The hadith of Abu Hurairah was mentioned in full in the chapter on the prohibition of selling an animal whose milk has been withheld to appear plentiful.