Sayyidah Qaylah Umm Bani Anmar (may Allah be pleased with her) said: I saw the Messenger of Allah (peace and blessings be upon him) at al-Marwah, coming out of the state of ihram after Umrah. I sat down beside him (peace and blessings be upon him) and said: O Messenger of Allah, I am a woman who buys and sells. Sometimes, when I want to sell an item, I ask a higher price for it than the one at which I want to sell it, then I keep lowering it until I sell it at the price I wanted; and when I want to buy an item, I offer a lower price for it than the one at which I want to buy it, then I keep raising it until I buy it at the price I wanted. The Prophet (peace and blessings be upon him) said: "O Qaylah, do not do that. When you want to sell an item, ask the very price at which you want to sell it, whether it is given or refused; and when you want to buy an item, offer the very price at which you want to buy it, whether it is given or refused."
Hadith Referenceالمعجم الكبير للطبراني / مسند النساء / 21467