Is there an expiation for a woman who vowed to donate all her jewelry if Allah cured her, then regretted it after her recovery? And is zakat due on this jewelry for eight years, and if so, is it from the jewelry itself or what?

A vow (nadhr) is disliked, but whoever vows obedience to Allah must fulfill it. A vow to donate all jewelry falls under two conditions:

1. If the jewelry constitutes all of the vower's wealth: It is sufficient for her to give one-third of the jewelry as charity. This is the opinion of Ahmad and Ibn Taymiyyah, who based it on the hadith of Abu Lubabah and Ka'b ibn Malik, may Allah be pleased with them both. 2. If she possesses other wealth besides the jewelry: She is obliged to donate all the jewelry as she vowed, because the vowed item is specific and an act of devotion, and it is obligatory to fulfill it unless it consumes all her wealth.

As for the zakat on jewelry, it must be paid for the past eight years, regardless of whether she will donate all the jewelry or only one-third of it. The zakat must be paid from her other wealth if she donates all the jewelry, or from the jewelry itself or her other wealth if she donates only one-third.