The fourth category is working animals: namely, camels owned by someone who hires them out for carrying loads. No zakah is due on them. This category existed before automobiles became widespread: one might find a man with one hundred or two hundred camels which he hired out to transport goods from one town to another. Zakah is only due on the income earned from their hire, once a lunar year has passed over it.
Thus, the categories are four, and the Lawgiver has explained each of them clearly and satisfactorily.
The broadest of these categories is trade goods, for zakah is due on them in all circumstances.
Zakah is due on camels, cattle, and sheep or goats when they graze freely for the entire year, or for most of it . . .
His statement, “Zakah is due on camels, cattle, and sheep or goats”: the subject of “is due” is zakah; that is, zakah is due on these three categories: first, camels; second, cattle; and third, sheep or goats.
His statement, “when they graze freely for the entire year, or for most of it”: “grazing freely” means that they graze on unrestricted pasture. Here, “unrestricted” does not mean the opposite of prohibited; rather, it refers to vegetation that grows by the act of Allah, exalted is He, rather than through our own cultivation. As for what we ourselves plant and then allow the animals to graze on, this does not render them freely grazing animals. For example, if someone has extensive tracts of land which he cultivates and then lets his grazing animals feed in those wide areas, they are not considered freely grazing animals.
His statement, “the entire year, or most of it”: “the year” functions as a time adverb modifying “grazing freely.” The meaning is that they graze on unrestricted pasture throughout the year, or for most of it. That they are freely grazing animals when they graze throughout the year is evident. As for their being considered freely grazing when they graze for most of the year, this is because the lesser period takes the ruling of the greater; thus, what is considered is the majority.