Caution: Translations of Quran and Ḥadīth may lead to possible misapplications and misinterpretations. This site is intended for students of sacred knowledge that are proficient in comprehending classical Arabic and have a strong foundation in Islamic sciences. Also note that religious injunctions rely on several aspects beyond what one may glean through reading individual aḥādīth.
bayhaqi:10885Abū ʿAbdullāh al-Ḥāfiẓ > Abū al-ʿAbbās > al-Rabīʿ > al-Shāfiʿī And al-Nnajsh

[Machine] That a man attends the goods being sold and he gives something for it, but he does not intend to buy it; the horse sellers follow his example and they give more for it than they would have given if they had not heard his bidding. So, whoever incites or encourages (others) to bid is considered a transgressor, if he knows about the prohibition of the Messenger of Allah ﷺ . He ﷺ said: "And selling is permissible, and it is not spoiled by the disobedience of a man who incites (others to bid)." He ﷺ said: "And there had been a sale made with someone who exceeded the covenant of the Messenger of Allah ﷺ , and the sale is valid." And it is allowed that someone who does not intend to buy adds to the price.  

البيهقي:١٠٨٨٥أَخْبَرَنَا أَبُو عَبْدِ اللهِ الْحَافِظُ ثنا أَبُو الْعَبَّاسِ أنا الرَّبِيعُ قَالَ قَالَ الشَّافِعِيُّ وَالنَّجْشُ

أَنْ يَحْضُرَ الرَّجُلُ السِّلْعَةَ تُبَاعُ فَيُعْطِي بِهَا الشَّيْءَ وَهُوَ لَا يُرِيدُ شِرَاءَهَا؛ لِيَقْتَدِيَ بِهِ السُّوَّامُ فَيُعْطُونَ بِهَا أَكْثَرَ مِمَّا كَانُوا يُعْطُونَ لَوْ لَمْ يَسْمَعُوا سَوْمَهُ فَمَنْ نَجَشَ فَهُوَ عَاصٍ بِالنَّجْشِ إِنْ كَانَ عَالِمًا بِنَهْيِ رَسُولِ اللهِ ﷺ قَالَ وَالْبَيْعُ جَائِزٌ لَا يُفْسِدُهُ مَعْصِيَةُ رَجُلٍ نَجَشَ عَلَيْهِ قَالَ وَقَدْ بِيعَ فِيمَنْ يَزِيدُ عَلَى عَهْدِ رَسُولِ اللهِ ﷺ فَجَازَ الْبَيْعُ وَقَدْ يَجُوزُ أَنْ يَكُونَ زَادَ مَنْ لَا يُرِيدُ الشِّرَاءَ