husband repudiates his wife for the third time, it triggers a "major" divorce (al-baynuna al-kubra), after which the couple cannot remarry without an intervening consummated marriage to another man. This is known as tahlil or nikah halala. Making the third pronouncement irrevocable prevents the husband from using repeated declarations and revocations of divorce as a means of pressuring his wife into making financial concessions in order to "purchase her freedom". It also acts as a deterrent to rash repudiations. Practice Women often entered marriage with substantial capital in the form of mahr and the trousseau provided by their family, which they were not obliged to spend on family expenses, and they frequently loaned money to their husbands. Because of this, and the financial obligations incurred, talaq could be a very costly and in many cases financially ruinous enterprise for the husband. Many repudiated women used the divorce payment to buy their ex-husband's share in the family house. In the historical record talaq appears to have been less common than khul'. Available evidence from Mamluk Egypt indicates that talaq was not the principal means of divorce. Talaq was considered to be disastrous for the woman because it deprived her of long-term protection and financial support, preventing her from remarrying, since this would cause her to lose child custody. This led to repudiation without good reason being considered socially improper. Studies of the Ottoman Levant showed that women could invalidate a declaration of talaq by stating that the husband had shown signs of "diminished rationality" when he made it, while others used a husband's unrevoked declaration of talaq to obtain divorce at a later date if they could prove that he made it. Talaq al-bid'ah and triple talaq Talaq types can be classified into talaq al-sunnah, which is thought to be in accordance with Muhammad's teachings, and talaq al-bid'ah, which are viewed as a bid'ah (innovation) deviations from it. Talaq al-sunnah is further subdivided into talaq al-ahsan, which is the least disapproved form of talaq, and talaq al-hasan. The ahsan talaq involves a single revocable pronouncement of divorce and sexual abstinence during the waiting period. The hasan divorce involves three pronouncements made during the wife's state of ritual purity with menstrual periods intervening between them, and no intercourse having taken place during that time. In contrast to talaq al-sunnah, talaq al-bid'ah does not observe the waiting period and irrevocably terminates the marriage.