Is the dowry permissible if it is to memorize Surat Al-Mulk and recite it every night after marriage? What are the proofs of its permissibility from the Sunnah? And does the marriage become null and void if its recitation is abandoned for a night?

The mahr (dowry) is a right of the wife and can be either wealth or a service. The fiancée's request that her mahr be the memorization of Surat Al-Mulk is a matter of scholarly disagreement, with the preponderant view being its permissibility, based on the hadith (definition) of the man whom the Prophet, peace and blessings be upon him, married off with what he had memorized from the Qur'an. However, if the intention is for the mahr to be the husband's memorization of Surat Al-Mulk, or merely its recitation, then it is not permissible, because the mahr must have financial value. The more cautious approach is for her to have a mahr with an agreed-upon financial value, and then she stipulates that he memorize the surah (definition). The invalidity of the mahr does not invalidate the marriage, and in such a case, the wife is entitled to a mahr al-mithl (a dowry equivalent to that given to women of similar status).