Sayyiduna Ubadah bin Samit (may Allah be pleased with him) narrates that the Messenger of Allah (peace and blessings be upon him) said: "Gold for gold, silver for silver, dates for dates, wheat for wheat, barley for barley, and salt for salt must be equal in amount and hand to hand. If these types differ, then sell as you wish, provided it is hand to hand (on the spot)."
Hadith Referenceالمنتقى ابن الجارود / كتاب البيوع والتجارات / 650
Hadith Gradingغلام مصطفےٰ ظهير امن پوري:صحیح
Hadith Takhrijاز غلام مصطفےٰ ظهير امن پوري:«صحیح مسلم : 1587»