Of their differences on the payment of zakah pertaining to plants and fruits, Ibn Rushd informs us: “The difference of opinion lies in the fact that some jurists confine paying of zakah to only those items of consumption which are generally agreed upon, while others go beyond those items and include dried fruits in them too. [The crux of the issue is]: What qualifies the four edible items [wheat, barley, dates, and dried grapes] for zakah? Are they subject to zakah because of their being delineated as such or because of their special import to the subsistence of life? Those who subscribe to the first view restrict payment of zakah to the four edibles, and those who subscribe to the second view extend the obligation to all land produce except for grass, firewood, and bamboo. There is a consensus on the latter being excluded from zakah. However, when it comes to the use of analogy based on a general statement, both groups rest on shaky ground.”
The saying of the Prophet, which uses the expression allazhi yaqtazhi, reads: “From what the heavens water, a tithe [is due], and from what is watered by irrigation [nazh] a half a tithe.” The relative pronoun ma is used to mean al-lazhi, which is a general expression. Allah, the Exalted, also says: “It is He who has brought into being gardens – both the cultivated ones and those growing wild – and the date palm, and fields bearing multiform produce, and the olive trees, and the pomegranate: all resembling one another and yet so different. Eat of their fruit when it comes to fruition, and give unto the poor their due on the harvest day…” [al-An’am 141].
Analogically speaking, zakah aims at counteracting poverty and this cannot be done through zakah on land produce which is edible and sustains life.
Restricting a general statement with this kind of analogical reasoning vitiates zakah on all land produce except ones which sustain life. Those who follow the general import of the Prophet’s saying add some more to the generally acknowledged four items. Excluded of course are the ones on which there is consensus.
Again, those who agree upon land produce of a substance kind often differ over whether it can be considered as being subsistent. Can analogical reasoning be the basis of what they agree upon or not? An example of such a disagreement is that of Malik and ash-Shaf’i regarding olives. Malik holds that zakah on olives is obligatory, while ash-Shaf’i is against it, according to a latter view expressed in Egypt. The reason for his disagreement is whether olives could be considered as food vital for life or not.