Wa `alaykum As-Salamu wa Rahmatullahi wa Barakatuh
In the Name of Allah, Most Gracious, Most Merciful.
All praise and thanks are due to Allah, and peace and blessings be upon His Messenger.
In this fatwa:
If because of circumstances beyond our control we cannot do each prayer on time, we may combine specific prayers.
In his response to your question, Sheikh Ahmad Kutty, a senior lecturer and Islamic scholar at the Islamic Institute of Toronto, Ontario, Canada, states:
Prayers have appointed times. We ought to try our best to perform them accordingly.
If, however, because of circumstances beyond our control we cannot do each prayer on time, we may combine specific prayers. It is called jam`.
We can combine Zhuhr and Asr by offering both of them one after the other either at the time of Zhuhr or at the time of Asr. However, we are not allowed to combine them with Maghrib or Isha.
We may combine Maghrib with Isha in the same manner by advancing Isha to the time of Maghrib or postponing Maghrib to the time of Isha. We are not allowed to combine Isha with Fajr or Fajr with Zhuhr.
The above ruling is based on the following report from Ibn Abbas: “The Messenger of Allah (peace be upon him) combined Zhuhr and Asr and Maghrib and Isha in Madinah (once) without reason of war or rain. On hearing his statement, someone asked: why did he do that? He replied, “To lift the hardship from his community (when they are in difficult situations).” (Muslim)
This report has been the basis for the ruling of some of the imams and eminent scholars that one may do this on unusual circumstances that are unavoidable.
Almighty Allah knows best.