´It was narrated from Abu Hurairah that the Prophet said:` "Taking oaths may help you to make a sale but it takes (blessing) away from the earnings "(Sahih )
Hadith ReferenceSunan an-Nasa'i / The Book of Financial Transactions / Hadith: 4466
Hadith Gradingالألبانی:صحيح | زبیر علی زئی:متفق عليه