ما هي الآية أو الحديث الذي يبيح زواج المسيار، وما هو مثال على فتوى لم يرد فيها نص شرعي ويكره فاعلها أن يطلع الناس عليها، ليكون تطبيقًا لمفهوم البر والإثم؟

Allah has legislated marriage with conditions and impediments. If the conditions are met and the impediments are absent, then the marriage is Islamically valid. Concealing the marriage from some people, such as a first wife, does not make it a sin. What weighs heavily on the heart is that which one fears might be a sin, and this does not apply to the misyar marriage because it is conducted openly with the presence of a guardian and witnesses.