Should one interrupt prayer to join an ongoing congregational prayer after realizing the last tashahhud in a previous prayer?

The virtue of congregational prayer is attained by joining the Imam before the first Taslim (salutation of peace). As long as you have joined him during the Tashahhud (final sitting), do not interrupt your prayer to join another congregation, for Allah Almighty says: "O you who have believed, obey Allah and obey the Messenger and do not invalidate your deeds."