Abu Salid al-Khudri reported Allah's Messenger (ﷺ) as saying:
Do not sell gold for gold, except like for like, and don't increase something of it upon something; and don't sell silver unless like for like, and don't increase some thing of it upon something, and do not sell for ready money something to be given later.
Reference: Sahih Muslim 1584 a In-book : Book 22, Hadith 93 USC-MSA web (English) : Book 10, Hadith 3845 (deprecated)
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