عَنْ أَبِي قَتَادَةَ رَضِيَ اللَّهُ عَنْهُ قَالَ سَمِعْتُ رَسُولَ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَآلِهِ وَسَلَّمَ يَقُولُ إِيَّاكُمْ وَكَثْرَةَ الْحَلِفِ فِي الْبَيْعِ فَإِنَّهُ يُنْفِقُ ثُمَّ يَمْحَقُ
It is narrated from Sayyiduna Abu Qatadah (may Allah be pleased with him) that the Messenger of Allah (peace and blessings be upon him) said: Avoid excessive swearing in trade, for although it makes the goods sell, the blessing is erased.