Does delaying the fulfillment of a vow to memorize the Qur’an after success in an exam have an effect, and what are the best surahs for memorization?

Whoever vows obedience to Allah must fulfill their vow, and it is not permissible for them to break it except in case of inability, in which case an expiation for breaking an oath becomes obligatory. Memorizing the Quran is one of the best acts of obedience, and the vow to do so must be fulfilled. If you specified certain surahs, you must memorize them. If you specified a certain amount, you must memorize that amount. If you did not specify anything, then memorizing whatever is easy for you from the Quran is sufficient. It is permissible to delay fulfilling the vow until a suitable opportunity arises, unless the wording of the vow necessitates immediate fulfillment. There is no preferred surah (definition) for memorization except Al-Fatihah, which is obligatory to memorize. It is recommended to start with the shorter surahs due to their ease.