Sahih al-Bukhari, Hadith 2087 ⓘ
Narrated Abu Huraira: I heard Allah's Messenger saying, "The swearing (by the seller) may persuade the buyer to purchase the goods but that will be deprived of Allah's blessing."
حَدَّثَنَا يَحْيَى بْنُ بُكَيْرٍ، حَدَّثَنَا اللَّيْثُ، عَنْ يُونُسَ، عَنِ ابْنِ شِهَابٍ، قَالَ ابْنُ الْمُسَيَّبِ إِنَّ أَبَا هُرَيْرَةَ ـ رضى الله عنه ـ قَالَ سَمِعْتُ رَسُولَ اللَّهِ صلى الله عليه وسلم يَقُولُ " الْحَلِفُ مُنَفِّقَةٌ لِلسِّلْعَةِ مُمْحِقَةٌ لِلْبَرَكَةِ " .
also referenced under: Book 34, Hadith 40 (In-Book) & Volume 3, Book 34, Hadith 300 (USC-MSA)