Sayyiduna Abu Hurayrah (may Allah be pleased with him) said that the Messenger of Allah (peace and blessings be upon him) said: "A dinar for a dinar, with no excess between them; and a dirham for a dirham, with no excess between them either."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب البيوع / 10486