Bismillah hir-Rahman nir-Rahim
Hadith: Qasam khaney se saman to jaldi bik jata hai lekin wo Qasam barkat ko mita deney wali hoti hai
Abu Hurairah Radiallahu anhu se rivayat hai ki Rasoollallah Sallallahu Alaihi Wasallam ne farmaya (dukandar ke) qasam khaney se saman to jaldi bik jata hai lekin wo qasam barkat ko mita deney wali hoti hai.
Sahih Bukhari, Vol 3, 2087
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Narrated Abu Huraira Radiallahu anhu : I heard Allah's Apostle Sallallahu Alaihi Wasallam saying, The swearing (by the seller) may persuade the buyer to purchase the goods but that will be deprived of Allah's blessing.
Sahih Bukhari, Vol 3, Book 34, No. 300