Answered by Shaykh Amjad Rasheed
Does someone who prays an obligatory prayer with a group outside the mosque (such as, for example, at home) attain the merit of the group prayer that is mentioned in hadiths even if the group prayer consists only of himself and his wife?
In the Name of Allah, Most Merciful and Compassionate
Yes, whoever prays a group prayer outside the mosque gains its reward as established in hadiths such as, “The group prayer is better than the individual prayer by 27 degrees.” However, the reward of praying with the group in the mosque is more complete, as has been explicitly stated by Imam Nawawi in al-Rawda. The group prayer can be performed by two people–the imam and the follower–even if the the follower is one’s wife, in which case both gain the reward of the group prayer.
(Translated by Hamza Karamali)