Is a sale valid if the specified currency items are not physically present at the time of the contract?
Chapter on Riba (Usury) and Exchange (Sarf)
Al-Mughni
Book of Sales
Primary text
In a sale where the consideration is specified in the debtor's liability (e.g., "I sell you an Egyptian Dinar for ten Dirhams"), the sale is valid even if neither party possesses the specified Dirhams or Dinars, provided they exchange possession (Qabd) in the meeting place (Majlis), even if by borrowing or another means. This is supported by Abu Hanifa and Al-Shafi'i.
Supporting text
A view ascribed to Malik states that currency exchange (Sarf) is not valid unless both specified items are present. Another narration opposes validity unless one of the two items is brought forth and specified. Zufar similarly held this, citing the Prophet's statement: "Do not sell what is absent of it for what is present (Najiz)." The justification is that if neither countervalue is specified, it constitutes selling debt for debt, which is invalid. The proof for validity when mutual possession occurs in the meeting is that it is treated as if they were present at the time of the contract. The prohibition is intended to prevent immediate assets from being exchanged for deferred assets, or what is taken possession of for what is not taken possession of, evidenced by the fact that if one item is specified, the sale is valid even if the other is absent, and possession in the meeting place serves as possession at the time of contract, analogous to 'item for item' and 'hand to hand'.