for silver as a debt, and he forbade that any absent part of it be sold for present, all of which are authentic (sahih) hadiths. Possession (qabd) in the session is sufficient, even if it lasts a long time; and if they both walk along together to the residence of one of them, or to the money changer, and take possession there, it is permissible. This is also the view of al-Shafi'i. Malik said: There is no good in that, because they have departed from their session. Our evidence is that they did not separate before taking possession, so it is like them being in a boat that is moving with them, or riding on a single mount that is walking with them. This is indicated by the hadith of Abu Barza al-Aslami, [in his statement] to the two who walked toward him from the side of the army: "I do not see that you have separated." If they separate before taking possession, the currency exchange (sarf) is void, due to the failure of its condition. If he takes possession of part of it, then they separate, it is void regarding what he did not take possession of, and regarding the equivalent of that in the consideration. Is it valid regarding what was possessed? There are two opinions, based on the principle of splitting the transaction (tafriq al-safqa). If one of them appoints an agent to take possession, and the agent takes possession before they separate, it is permissible, and the possession by his agent stands in place of his own possession, regardless of whether the agent left the session before the possession or did not leave it. If they separate before the agent takes possession, it is void, because possession in the session is a condition, and it has been missed. If they give each other the option (takhayara) before possession in the session, the contract is not voided by that, because they did not separate before possession. It is possible that it would be void if we were to say the contract is binding, which is the school of al-Shafi'i, because the contract would not have any option left in it before possession, making it similar to the case if they had separated. The correct view is the first one; for the condition is possession in the session, and it has been met, and stipulating possession before the contract becomes binding is an arbitrary requirement without evidence. Furthermore, it is invalidated by the case where they give each other the option before the currency exchange, then they enter into the exchange, for the exchange occurs as binding and valid before possession, and then possession is stipulated in the session.