Is it permissible to look at the meanings of the words found in the margins of the Mus'haf while reciting from it during Qiyam al-Layl, if that does not affect the recitation or the humility (khushu')?

It is permissible for someone performing a supererogatory prayer to read from the Mus'haf, according to the majority of scholars. However, one should not contemplate the meanings of the verses during prayer, as this leads to a lack of khushu' (devotional humility) and distracts the worshipper. The slightest distraction of a person in prayer is at the lowest level of reprehensibility. For this reason, scholars disliked the adornment of mosques. The worshipper should study the interpretation of the verses before commencing prayer, because combining recitation with contemplating the meanings of the written verses while maintaining khushu' is unlikely.