If they are of the same group (sharing the same ‘illah), but different kinds, such as wheat for barley or silver for gold, they must be traded hand to hand, but not necessarily equal for equal. If they belong to different groups (not sharing the same ‘illah), such as silver for wheat, or if one of the two objects of sale is not usurious, such as camels for wheat, it is permissible to trade them with deferment of one item and increase. (Even if we consider the ‘illah for gold and silver being usurious items that they are measured by weight, as currencies, they may always be used as payment for other usurious items measured by weight with deferment of the price in deferred payment sales or the commodity in advance payment sales.)

Exchange of Non-Usurious Items
As for items which are not considered to be potentially usurious, you may exchange them with a difference in measure and with deferment. One, for instance, may sell three laptops delivered now for a car received in two months. However, there is a disagreement regarding exchanging properties of the same kind with a difference (e.g., two camels for one) when part of the transaction is deferred.

(a) + (-H): not allowed. In addition to the rational proof, they cited a hadith with controversial authenticity from Samurah ibn Jundub, in which the Prophet (SA) was quoted to have prohibited selling an animal for an animal in a deferred transaction. (-M) also agreed with this position as long as the traded properties have the exact uses/benefits.

(A) + (+S) allowed this deferment with an increase, supported by reports that the Companions, including ‘Ali, Ibn ‘Umar, and Ibn ‘Abbâs (RAHUM) were involved in transactions of this nature.