Is it obligatory to re-pay the Zakat that was given to the husband to settle his debt, knowing that he was not an indebted person (gharim) in hardship, and that the Zakat payer was unaware of the ruling at the time?

It is permissible for a woman to give Zakat to her husband if he is eligible. However, if he is not eligible, it is impermissible and incorrect to give it to him. If a wife gives Zakat to her husband, believing him to be eligible because he is in debt, but then discovers that he is wealthy and capable of repaying the debt, she must give the Zakat again, because she gave it to someone who was not eligible for it. Some scholars hold the view that Zakat is not valid even if it was given to someone believed to be poor but who later turned out to be wealthy, especially if the recipient's condition is not hidden from the Zakat giver, as in the case of a husband.