What is the ruling on conditioning marriage upon a stipulation, knowing that the family was able to free the girl from the kidnapper who stipulated marriage for her return? Is the girl considered to be under the man's marital authority or divorced due to a corrupt marriage contract? And what is the ruling on the iddah (waiting period) in this case?

If a girl and her guardian are coerced into marrying a man who kidnapped her, in order to free her from him, the marriage contract is invalid because it stems from prohibited coercion in marriage. The girl is not considered his wife.

Regarding the waiting period (iddah): If he did not consummate the marriage with her, she has no iddah. If he did consummate the marriage, the preponderant opinion is that she must observe a period of istibraa' (clearing of the womb) with one menstrual cycle, because the contract is invalid. This is the view preferred by Shaykh al-Islam Ibn Taymiyyah and Ibn Uthaymeen, who argued that Allah mandated three menstrual cycles for divorced women from their husbands, and that a woman who seeks khul' (divorce initiated by the wife) observes an iddah of one menstrual cycle. A woman who committed zina (unlawful sexual intercourse) or was engaged in sexual intercourse due to a misconception (shubhah) is even more deserving of this rule.