Is it permissible for the husband to retrieve part of the Mahr (dowry) after divorcing his wife, when she was granted Khulʿ (divorce at the wife's instance) and he had not yet consummated the marriage, by agreement with her guardian, if the wife was the reason for the divorce?

The majority of jurists are of the opinion that a valid seclusion (khalwa sahihah) establishes the full mahr (dowry) as due, provided the woman does not prevent herself [from intercourse]. They base their reasoning on the rulings of the Rightly Guided Caliphs, such as the statement of Umar and Ali (may Allah be pleased with them): "If a door is closed and a curtain is lowered, then she is entitled to the full dowry, and she must observe the waiting period ('iddah)." However, if the wife prevents herself, then she is only entitled to half the mahr. This is the view held by Ibn Qudamah, Ibn Taymiyyah, and others.