Ubadah bin Samit Al-Ansari, head of the army unit, the Companion of the Messenger of Allah (ﷺ), went on a military campaign with Mu'awiyah in the land of the Byzantines. He saw people trading pieces of gold for Dinar and pieces of silver for Dirham. He said: "O people, you are consuming Riba (usury)! For I heard the Messenger of Allah (ﷺ) say: 'Do not sell gold for gold unless it is like for like; there should be no increase and no delay (between the two transactions).'" Mu'awiyah said to him: "O Abu Walid, I do not think there is any Riba involved in this , except in cases where there is a delay." 'Ubadah said to him: "I tell you a Hadith from the Messenger of Allah (ﷺ) and you tell me your opinion! If Allah brings me back safely I will never live in a land in which you have authority over me." When he returned, he stayed in Al-Madinah, and 'Umar bin Khattab said to him: "What brought you here, O Abu Walid?" So he told him the story, and what he had said about not living in the same land as Mu'awiyah. 'Umar said: "Go back to your land, O Abu Walid, for what a bad land is the land from where you and people like you are absent." Then he wrote to Mu'awiyah and said: "You have no authority over him; make the people follow what he says , for he is right."