عَنْ أَبِي هَرَيْرَةَ رَضِيَ اللّهُ عَنْهُ: أَنَّ رَسُولَ اللّهِ صَلَّى اللّهُ عَلَيْهِ وَسَلَّمَ قَالَ: «لا تَنَاجَشُوا» مُتَّفَقٌ عَلَيْهِ.
Abu Hurayrah (may Allah be pleased with him) reported that the Messenger of Allah (peace and blessings be upon him) said: "Do not engage in najsh (bidding up a price without intending to buy)." Agreed upon (al-Bukhari and Muslim).
الشرح · explanation
لا تناجشوا: النجش: هو الزيادة في السلعة لا بقصد الشراء، وإنما ليغرّ غيره ويخدعه
"Do not engage in najsh": najsh is raising the price of goods without intending to buy, but only to deceive another and cheat him.
الدروس · lessons
تحريم النجش لما فيه من الغشّ والخداع. النهي عن كل ما يضر بالمسلم في بيعه وشرائه.
The prohibition of najsh because of the cheating and deception it involves. The prohibition of everything that harms a Muslim in his buying and selling.