It is narrated from Abu Ash'ath (may Allah have mercy on him) that we fought a battle under the leadership of Sayyiduna Amir Muawiyah (may Allah be pleased with him). We obtained gold and silver as spoils of war, so Sayyiduna Muawiyah (may Allah be pleased with him) ordered a man to sell this booty in exchange for the grants (salaries) that people were to receive (i.e., the price would be collected when the grants were distributed). People hurried to buy, but Sayyiduna Ubadah (may Allah be pleased with him) stood up and forbade the people, so they returned the gold and silver to the representative of Sayyiduna Muawiyah (may Allah be pleased with him). He went and complained to Sayyiduna Muawiyah (may Allah be pleased with him). Sayyiduna Muawiyah (may Allah be pleased with him) addressed the people and said: "What has happened to the people that they narrate the ahadith of the Messenger and attribute such things to him (we too are companions, may Allah be pleased with them all)? We did not hear such from the Prophet (peace and blessings be upon him)." Sayyiduna Ubadah (may Allah be pleased with him) stood up again and said: "By Allah, we will certainly narrate the ahadith that we heard from the Messenger of Allah (peace and blessings be upon him), even if Muawiyah dislikes it. The Messenger of Allah (peace and blessings be upon him) 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, alike for alike, and hand to hand (immediate exchange).'"
Hadith Referenceالسنن المأثورة / باب في البيوع / 222