It is narrated from ‘Ubadah bin Samit (may Allah be pleased with him) that the Messenger of Allah (ﷺ) said: “Do not sell gold for gold, silver for silver, wheat for wheat, barley for barley, dates for dates, or salt for salt except equal for equal, same for same, and hand to hand. But sell gold for silver, silver for gold, wheat for barley, barley for wheat, dates for salt, and salt for dates as you wish, provided it is hand to hand.” One of them reduced the amount of dates or salt, and one of them added: “Whoever gives more or asks for more has engaged in usury.”
Hadith Referenceمسند الإمام الشافعي / كتاب البيوع / 1395
Hadith Takhrijصحيح اخرجه النسائي البيوع، باب بيع البر بالبر (4564) ، (4565) وابن ماجة، التجارات، باب الصرف وما لا يجوز متفاضلا يدا بيد (2254) ومسلم ، المساقاة، باب الصرف وبيع الذهب بالورق نقدا (1587) - عن طريق آخر۔