Beware of excessive swearing (by Allah) in sale transactions, for it sells (the goods) then erases (the blessing). [Muslim]
"""«إيَّاكُمْ وكَثْرَةَ الحَلِفِ في البيع، فإنه يُنَفِّقُ ثم يَمْحَقُ». [صحيح.] - [رواه مسلم.]"" "