Answered by Sidi Tabraze Azam
Question: As’Salamu Alaykum,
Is it disliked to read surahs in any order when performing salah or does it have to be in order? Did our Prophet pray in this manner? Does this vary in different madhabs and if so why? Which is the correct way or are they all correct? When praying 4 rakats salat in the 3rd and 4th rakat does one read another surah after reciting al-Fatiha? If someone does recite another surah after al-Fatiha is this wrong to do this? again does this differ amongst the madhabs?
Answer: Wa alaikum assalam wa rahmatullahi wa barakatuh,
I hope you are in the best of health and spirits insha’Allah.
I apologize for the delay in answering your question.
 According to the Hanafi school, in obligatory prayers, it is disliked to recite a chapter (sura) in the first cycle (rak`at) and then a chapter (sura) in the second cycle (rak`at) which comes before the first one in the Qur’anic order; for example, reciting Surat al-Nas and then Surat al-Falaq.
 In the third and fourth cycles (rak`ats) of an obligatory prayer one only recites the Fatiha, does glorifications (tasbihs) or remains silent for the extent of three glorifications (tasbihs). It would be slightly disliked (makruh tanzihan) to recite after the Fatiha in the final two cycles (rak`ats) of obligatory prayers.
 As for the recitation in voluntary (nafl) prayers, it is necessary (wajib) to add a chapter (sura) to the Fatiha in every cycle (rak`at) of the prayer.
[Shurunbulali, Maraqi al-Falah/ Ibn Abidin, Radd al-Muhtar/ Ibn Nujaym, al-Bahr al-Raiq]
Rulings do differ within the different schools of thought (madhabs), however, all four schools are completely sound and rightly guided. Differences of opinion are a mercy.
For further readings on the different schools (madhabs), please see the following:
And Allah knows best.
Checked & Approved by Faraz Rabbani