Hasan says that by Allah Almighty’s statement { وَالَّذِینَ فِی أَمْوَالِہِمْ حَقٌّ مَعْلُومٌ}, what is meant is the obligatory zakat.

Ibrahim says that (the Companions) when they were given gifts (grants), they would give charity from it.

Hazrat Amr bin Maimoon narrates that Walid bin Abdul Malik took twenty thousand (dirhams) from a person among the Ahl al-Dhimma whose kunyah was Abu Aisha (may Allah be pleased with her) and deposited them into the Bayt al-Mal. Then, when Hazrat Umar bin Abdul Aziz became the caliph, his son came to you and conveyed his story of oppression to you. You wrote to Maimoon that his wealth should be returned to him and the zakat for this year should also be collected. If this wealth had not been "dhamar" (wealth and debt for which there is no hope of return), I would have collected the zakat for the previous years as well.