What is the ruling on mixing after a sale when each owner previously owned half a Nisab separately?
Chapter on Zakat on Sheep
Al-Mughni
Book of Zakat
Primary text
If each owner possessed half a Nisab separately and then sold it to the other, and the mixture was maintained, the effect of the mixture is not interrupted. This is because an individual's property is aggregated with itself, as if the full eighty sheep remained mixed throughout. This applies even if they traded less than half the Nisab separately before mixing.
Supporting text
If they traded more than half the property separately, the effect of the mixture is nullified because a condition for mixture is that the combined total must reach a Nisab; remaining below the Nisab in separation renders them individual owners again.