Question: If one is shortening Night Prayer behind someone praying Sunset Prayer, what do you do on the third cycle?
Answer: Dear questioner,
Thank you for your important question. May Allah accept all your prayers and give you light and success in all your journeys.
The first thing we need to understand is that is is only valid to shorten a prayer if one is not praying behind someone praying the full amount. If the imam is praying the full amount of any prayer (such as the two raka’ts of Jumua, or the three raka’ts of Maghrib), the follower cannot shorten any prayer behind him. (Bushra al-Karim, Bashin)
In view of this, when one wants to shorten Isha behind someone praying Maghrib, it is not permissible, and not of value. Such a prayer would have to be repeated.
The other point is that although it is valid to pray basically any prayer behind any other prayer (sunna behind obligatory, Dhuhr behind Asr, etc.), it is not necessarily sunna. Rather is it is better not to pray one obligatory prayer behind someone praying any other obligatory prayer. (Niyahat al-Muhtaj, Ramli)
So, the best thing to do would be to pray Maghrib in the group and then join and/or shorten Isha by oneself or with a group who are praying Isha.
It is also worth noting that joining prayers is by default not recommended [sunna], and rather merely permissible. (Bushra al-Karim, Bashin)
I pray this helps.
[Ustadh] Farid Dingle
Checked and Approved by Shaykh Faraz Rabbani
Ustadh Farid Dingle has completed extensive years of study in the sciences of the Arabic language and the various Islamic Sciences. During his studies, he also earned a CIFE Certificate in Islamic Finance. Over the years he has developed a masterful ability to craft lessons that help non-Arabic speakers gain a deep understanding of the language. He currently teaches courses in the Arabic Language