Praise be to Allah.
If a person is owed money by a rich man that reaches the amount of the nisaab, or when added to the money he has would bring the amount up to the nisaab, he must pay zakaah on it, and when he gets the money back he should pay zakaah for the time that has passed, whether it is a year or more. If he pays zakaah on it before he gets it, that is fine. If the person who owes the money is not rich, he should pay zakaah one year after he gets the money, even if more than a year has passed. This is one opinion reported from Imaam Ahmad; it is also the opinion of Maalik and of Shaykh Muhammad ibn ‘Abd al-Wahhaab (may Allaah have mercy on him). Allaah is the Source of strength. May Allaah bless our Prophet Muhammad and his family and companions.