Is it permissible to combine the 'Isha prayer with the congregation of another mosque after I have prayed Maghrib in a different mosque?

For the validity of combining two prayers (Jam' Taqdim), continuity between them is a condition. If a break occurs, the combination becomes invalid. The estimation of the break depends on common practice, unless the break is minor, in which case it does not affect the validity.

Some scholars are of the opinion that it is not a condition to perform the two combined prayers in one mosque. So, if one performs one of them at home and the other with the Imam, there is no harm in it.

Shaykh al-Islam Ibn Taymiyyah held the view that continuity between the two combined prayers is not a condition.