Is Zakat obligatory on a deposited amount that ceased to yield profit for four years and was later reclaimed in installments?

Stipulating a known profit or guaranteeing the capital in a mudarabah contract is impermissible and invalidates the contract. In such a case, all profit belongs to the capital owner, and the mudarib (working partner) is entitled to a fair wage (ajr al-mithl). If the mudarabah is invalid, the due profits must be determined, and all of them belong to the capital owner. The mudarib is entitled to a fair wage; if anything remains, it goes to the capital owner, and if there is a deficit, the capital owner pays it to the mudarib. If the capital has not been lost, or if it was lost due to the mudarib's negligence, it is considered a debt owed by him, and its zakat becomes due for past years once it is received. However, if the capital was lost without negligence on the mudarib's part, it is not due to the capital owner and must be returned to him, regardless of whether the mudarabah was valid or invalid.