I heard Allah's Messenger (ﷺ) saying, "The swearing (by the seller) may persuade the buyer to purchase the goods but that will be deprived of Allah's blessing."
Sahih al-Bukhari Book 34, Hadith 40
← Previous Hadith My father bought a slave who practiced the profession of cupping. (My father broke the slave's instruments of cupping). I asked my father why he had done so. He replied, "The Prophet (ﷺ) forbade the acceptance of the price of a dog or blood, and also forbade the profession of tattooing, getting tattooed and receiving or giving Riba, (usury), and cursed the picture-makers."

Sahih al-Bukhari Book 34, Hadith 39 Next Hadith → A man displayed some goods in the market and swore by Allah that he had been offered so much for that, that which was not offered, and he said so, so as to cheat a Muslim. On that occasion the following Verse was revealed: "Verily! Those who purchase a small gain at the cost of Allah's covenant and their oaths (They shall have no portion in the Hereafter ..etc.)' (3.77)

Sahih al-Bukhari Book 34, Hadith 41