Umar bin Muhammad bin Ali bin Abi Talib (may Allah have mercy on him) narrates from his father (Muhammad bin Ali (may Allah have mercy on him)), from his grandfather Sayyiduna Ali (may Allah be pleased with him), that he said: The Messenger of Allah (peace and blessings be upon him) said: "A dinar for a dinar and a dirham for a dirham (on an equal basis), with no excess between them. So whoever needs gold, let him exchange (it) for silver, and whoever needs silver, let him exchange it for gold, (but this deal) must be 'ha' wa ha'' (hand to hand and on the spot)."
Imam al-Tabarani (may Allah have mercy on him) said: "This hadith is narrated from Sayyiduna Ali (may Allah be pleased with him) only with this chain, and Ibrahim al-Shafi'i (may Allah have mercy on him) is alone in narrating it."
Hadith Referenceالمعجم الأوسط / باب الميم / 6347
Hadith Takhrij«أخرجه الحاكم فى «المستدرك» برقم: 2321، وابن ماجه فى «سننه» برقم: 2261، والدارقطني فى «سننه» برقم: 2880»