Muhammad bin 'Abdul A'la محمد بن عبد الأعلى · The Book of Oaths and Vows

"You are setting up rivals (to Allah) and associating others (with Him). You say: 'Whatever Allah wills and you will,' and you say: 'By the Ka'bah.'" So the Prophet commanded them, if they wanted to swear an oath, to say: "By the Lord of the Ka'bah;" and to say: "Whatever Allah wills, then what you will."

"In Al-Madinah we used to buy and sell Wasqs (of goods), and we used to call ourselves Samasir (brokers), and the people used to call us like that. The Messenger of Allah came out to us one day, and called us by a name that was better than that which we called ourselves and which the people called us. He said: 'O Tujjar (traders), your selling involves (false) oaths and lies, so mix some charity with it.'"

"They do not bring any good; they are just a means of taking wealth from the miserly."