How does one make up for a missed Asr prayer due to a legitimate excuse, when the Maghrib Adhan is called before they pray Asr? Should they pray Asr first, or pray Maghrib in congregation and then make up Asr?

Delaying prayer beyond its prescribed time is a grave sin, unless there is a legitimate شرعي (Shar'i) excuse such as sleep or forgetfulness. This prohibition has been specifically mentioned, particularly concerning the 'Asr prayer. It is not permissible for anyone to delay prayer beyond its time without an excuse, even in a state of combat, where combining prayers or praying according to the circumstances is allowed. Therefore, whoever intentionally misses a prayer has committed a grave major sin. According to the majority of scholars, they must make it up (qada'). So, if someone misses the 'Asr prayer until the time for Maghrib enters, they should pray 'Asr first, then Maghrib. If the congregational prayer for Maghrib is established, they should intend to pray 'Asr with the congregation, complete it, and then pray Maghrib.