709 – Abu Saʿīd al-Khudrī (may Allah be pleased with him) reported that the Messenger of Allah ﷺ said: “Do not sell gold for gold unless it is equal for equal, and do not let part of it exceed another part. Do not sell silver for silver unless it is equal for equal, and do not let part of it exceed another part. Nor may any of them be sold when one side is deferred while the other is immediate.” Agreed upon. (1)

Vocabulary of the ḥadīth
– al-dhahab bi’l-dhahab (gold for gold): the sale of one for the other, a transaction known as ṣarf (currency exchange). It is called ṣarf because it departs from the usual sales rules in that neither party may dispose of what he has bought until mutual possession has taken place; it is also said to derive from the requirement that the two amounts be exactly equal in weight.
– mithlan bi-mithl (equal for equal): the two commodities must be identical and of the same weight.
– wa-lā tushiffū baʿḍahā ʿalā baʿḍ (do not let part of it exceed another part): from the verb ashafa; shaf means an increase or profit—i.e., do not give preference by adding any amount over the other.
– al-wariq: minted silver; its plural is awrāq. Al-Fārābī said: al-wariq refers to money in the form of dirhams, and al-riqqah is a collective term for it.
– bi-nājaz (for something on the spot): from najz, meaning what is present and delivered; here it denotes the item that is immediately exchanged, as opposed to what is deferred or absent at the time of the contract.
– baʿḍahā ʿalā baʿḍ (part of it over another part): the pronoun refers to gold and silver; the preposition “ʿalā” indicates any excess—whether increase or decrease—between the two sides.