The ruling on one who joins a prayer and remembers the one before it

Question:
A message was sent by one of the listening brothers, who preferred not to mention his name. He asks Your Eminence: If I joined the 'Isha' prayer, for example, and I am praying alone, and then I remember that I did not pray Maghrib, is it permissible for me to change my intention to the Maghrib prayer, given that I have not yet bowed in the first rak'ah? And if I am in a congregation, do I cut off my prayer and pray Maghrib first before 'Isha', thereby missing the virtue of the congregation? May Allah reward you with good.

Answer:
If you remember that you did not pray Maghrib, you cut off the 'Isha' prayer, intending to cut it off, then you begin with the takbirat al-ihram intending Maghrib, whether you are alone or with the congregation. There is no harm in your intention differing from the congregation's intention. There is no blame on you for praying behind someone who is praying 'Isha' while you are intending Maghrib, because you have not prayed it. You cut off the intention of 'Isha' by intention, then you say the takbirat al-ihram intending Maghrib, whether you are alone or with the imam. Then, after finishing, you pray 'Isha' afterwards, and praise be to Allah.