it does not prevent the obligation, because the subject can accommodate both of them together. If what was vowed is less than the amount of the Zakat, the amount of the Zakat is mandatory, and the vow is included within it, according to one of the two opinions, and according to the other, both must be paid in full.

Section: If we say that debt does not prevent the obligation of Zakat on manifest wealth, and the ruler interdicts [the person] after the Zakat becomes mandatory, he does not have the right to pay it, because his discretion over his wealth has been severed. If he acknowledges it after the interdiction, his acknowledgment is not accepted, and it remains upon his liability like the debt of a human being. It is possible that it lapses if he is interdicted before the possibility of paying it, just as if his wealth were destroyed. If the creditors acknowledge the obligation of Zakat upon him, or it is established by evidence, or he had acknowledged it before being interdicted, it is mandatory to pay it from the wealth, and if they do not pay it, they bear the sin for it.

Section: If a slave prepared for trade commits a crime, and the compensation (arsh) attaches to his person, it prevents the obligation of Zakat on him if it reduces the Nisaab; because it is a debt. If it does not reduce the Nisaab, it prevents the Zakat on the amount equal to the compensation.

461 - Issue: He said: "And if he has a debt upon a solvent person, there is no Zakat upon him until he collects it, then he pays for the past [years]."

The summary of this is that there are two types of debt. The first is a debt upon one who acknowledges it and is willing to pay it. Its owner must pay its Zakat, except that he is not obligated to pay it until he collects it, then he pays for the past, which was narrated from Ali, may Allah be pleased with him. This is the opinion of al-Thawri, Abu Thawr, and the People of Opinion (Ashab al-Ra'y). Uthman, Ibn Umar, Jabir, may Allah be pleased with them, Tawus, al-Nakha'i, Jabir ibn Zayd, al-Hasan, Maymun ibn Mihran, al-Zuhri, Qatada, and Hammad ibn Abi Sulayman [said...]