Musannaf Ibn Abi Shaybah

Hazrat Mahmool, the freed slave of Aal Ammarah, says that I sold two sheets to a man and made a condition that if you open one sheet, the sale of both will become binding. He opened one sheet, then he was not satisfied with the sale and came back to return them to me. I refused to take them back and took this case to Qazi Shurayh. He said, "It is your consent, not his, whereas a sale is based on mutual consent."