He reported God’s Messenger as saying, "Do not sell gold for gold unless it is like for like, and do not make one amount greater than the other; do not sell silver for silver unless it is like for like, and do not make one amount greater than the other; and do not sell for ready money something to be given later*.” A version has, "Do not sell gold for gold or silver for silver unless both are of equal weight.” (Bukhari and Muslim.) * Payment is not to be made till the goods are received.
Hadith Referenceمشكوة المصابيح / كتاب البيوع / 2810
Hadith Gradingالألبانی:مُتَّفَقٌ عَلَيْهِ | زبیر علی زئی:متفق عليه
Hadith Takhrij´تحقيق و تخريج: محدث العصر حافظ زبير على زئي رحمه الله` «متفق عليه، رواه البخاري (2177) و مسلم (75. 77 /1584)»